Phylogenetic assessment of heterotrophic bacteria from a water distribution system using 16S rDNA sequencing

Determination of a heterotrophic plate count (HPC) for drinking-water samples alone is not enough to assess possible health hazards associated with sudden changes in the bacterial count. Speciation is very crucial to determine whether the population includes pathogens and (or) opportunistic pathogens. Most of the isolates recovered from drinking water samples could not be allocated to a specific phylogenetic branch based on the use of conventional diagnostic methods. The present study had to use phylogenetic analysis, which was simplified by determining and using the first 500-bp sequence of the 16S rDNA, to successfully identify the type and species of bacteria found in the samples. Gram-positive bacteria alpha-, beta-, and gamma-Proteobacteria were found to be the major groups representing the heterotrophic bacteria in drinking water. The study also revealed that the presence of sphingomonads in drinking water supplies may be much more common than has been reported so far and thus further studies are merited. The intermittent mode of supply, mainly characterized by water stagnation and flow interruption associated possibly with biofilm detachment, raised the possibility that the studied bacterial populations in such systems represented organisms coming from 2 different niches, the biofilm and the water column.     

20-HETE and EETs in Diabetic Nephropathy: A Novel Mechanistic Pathway

Diabetic nephropathy (DN), a major complication of diabetes, is characterized by hypertrophy, extracellular matrix accumulation, fibrosis and proteinuria leading to loss of renal function. Hypertrophy is a major factor inducing proximal tubular epithelial cells injury. However, the mechanisms leading to tubular injury is not well defined. In our study, we show that exposure of rats proximal tubular epithelial cells to high glucose (HG) resulted in increased extracellular matrix accumulation and hypertrophy. HG treatment increased ROS production and was associated with alteration in CYPs 4A and 2C11 expression concomitant with alteration in 20-HETE and EETs formation. HG-induced tubular injury were blocked by HET0016, an inhibitor of CYPs 4A. In contrast, inhibition of EETs promoted the effects of HG on cultured proximal tubular cells. Our results also show that alteration in CYPs 4A and 2C expression and 20HETE and EETs formation regulates the activation of the mTOR/p70S6Kinase pathway, known to play a major role in the development of DN. In conclusion, we show that hyperglycemia in diabetes has a significant effect on the expression of Arachidonic Acid (AA)-metabolizing CYPs, manifested by increased AA metabolism, and might thus alter kidney function through alteration of type and amount of AA metabolites.     

Trypanosomatid phosphoglycerate mutases have multiple conformational and oligomeric states

Three structurally distinct forms of phosphoglycerate mutase from the trypanosomatid parasite Leishmania mexicana were isolated by standard procedures of bacterial expression and purification. Analytical size-exclusion chromatography coupled to a multi-angle scattering detector detected two monomeric forms of differing hydrodynamic radii, as well as a dimeric form. Structural comparisons of holoenzyme and apoenzyme trypanosomatid cofactor-independent phosphoglycerate mutase (iPGAM) X-ray crystal structures show a large conformational change between the open (apoenzyme) and closed (holoenzyme) forms accounting for the different monomer hydrodynamic radii. Until now iPGAM from trypanosomatids was considered to be only monomeric, but results presented here show the appearance of a dimeric form. Taken together, these observations are important for the choice of screening strategies to identify inhibitors of iPGAM for parasite chemotherapy and highlight the need to select the most biologically or functionally relevant form of the purified enzyme.     

Relationship between histamine and physiological changes during the early response to nasal antigen provocation

Toinvestigate the temporal relationships of mediator release andphysiological changes during the early response to allergen, wechallenged allergic individuals intranasally with antigen and followedtheir responses. This was done by using small filter paper disks tochallenge one nostril and collect secretions from both the challengedand the contralateral nostril, thus enabling us to evaluate thenasonasal reflex. There was a significant increase insneezing after allergen challenge that peaked within 2 min and returnedto baseline. The weights of nasal secretions as well as nasal symptomsincreased immediately and remained significantly elevated for 20 min inboth nostrils. Nasal airway resistance increased slowly, reaching itspeak at ~6 min after challenge on the ipsilateral side, but it didnot change on the contralateral side. Histamine levelspeaked 30 s after removal of the allergen disk on the side ofchallenge, whereas albumin levels peaked after those of histamine.Lactoferrin paralleled the increase in secretion weights and occurredin both nostrils. Increasing doses of antigen produced dose-dependentincreases in all parameters, whereas control challenges produced noresponse. These studies describe a human model for the evaluation ofthe allergic response that is capable of simultaneously measuringmediator release and the physiological response, including thenasonasal reflex. This model should prove useful instudying the mechanism of allergic rhinitis in humans.     

Isotope tracing in adult zebrafish reveals alanine cycling between melanoma and liver

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Cation uptake from bentonite suspensions by excised barley roots

Summary The net uptake of Na, K, or Ca by excised barley roots as influenced by the amount and kind of other cation was studied from bi-ionic and tri-ionic bentonite suspensions. The net uptake of Na or K from the Na-Ca or K-Ca system followed the concentration of soluble Na or K in the system. Calcium in both systems was taken up by the excised roots only at the 80 and 100 per cent Ca levels. At lower levels of Ca, the roots lost some of their initial calcium contents to the suspensions. The net uptake of Na or K from the Na-K system was in agreement with the concentrations of soluble Na or K in the system. At the various levels of Na or K, some of the initial calcium of the roots was lost to the suspensions. In the Na-K-Ca system, Na uptake gradually decreased with the increase of Ca level. Calcium was not absorbed by the roots at the various Ca levels. However, calcium greatly enhanced K uptake from this system. Part of a dissertation submitted by the senior author in partial fulfillment of requirements for the Ph. D. degree.     

Identification by cross-linking of a neuronal acceptor protein for dendrotoxin,a convulsant polypeptide

Dendrotoxin, a lijow molecular weight protein from the venom of Dendroaspis angusticeps, is known to be a potent convulsant that attenuates one type of voltage-sensitive K⁺ channel in guinea-pig hippocampus. A biologically active preparation of ¹²⁵I-labelled dendrotoxin has been cross-linked to its high-affinity protein acceptor in synaptic plasma membranes from rat cerebral cortex. On SDS gel electrophoresis, a complex with a M_r of 72,000 was observed which, assuming one toxin molecule is attached, yields an apparent size of 65,000 for this subunit of the acceptor. Unlike dendrotoxin, low concentrations of β-bungarotoxin, another pre-synaptically acitve toxin, do not inhibit its labelling.     

Further studies on cation uptake from bentonite suspensions by excised barley roots

Summary The net uptake of Na, K, Li, and Ca or Mg by excised barley roots was studied from bi-ionic and tri-ionic bentonite suspensions. The net uptake of Li from Li-Ca system progressed linearly with progressive Li levels and was related to the concentration of soluble lithium. Calcium in this system was taken up only at the 100 per cent Ca level. At lower Ca levels calcium was lost from the roots to the suspensions. In K-Mg and Na-Mg systems the net uptake of Na or K by the excised roots was related to the concentration of the cation in the solution phase. Magnesium uptake took place at 80 and 100 per cent Mg levels. It was much less than that of K or Na at similar levels. At lower levels of Mg the roots lost some of their initial Mg contents to the suspensions. In the Na-K-Mg system magnesium was not taken up by the excised roots. Sodium uptake was not practically affected by the Mg level, but K uptake was greatly enhanced by magnesium.     

Varicocele and Infertility in Men

Varicocele is an important cause of infertility in men. The exact mechanism by which varicocele depresses spermatogenesis is unknown but probably the retrograde flow of blood rich in catecholamines into the testes plays a major role.Because subfertile semen qualities are present in a large percentage of men with varicocele and because the response to surgical procedures is very good, high ligation of the left internal spermatic vein is recommended in men with varicocele and infertility.