Blood brain barrier breakdown in brain edema following cold injury is mediated by microvascular polyamines

A focal freeze injury to rat cerebral cortex induces an early (less than 5 min) increase in brain ornithine decarboxylase activity and an accumulation of polyamines involving cerebral microvessels. This polyamine synthesis correlates with the abnormal increase in microvascular permeability, monitored by uptake of Evans Blue and sod. fluorescein. The ornithine decarboxylase inhibitor alpha-difluoromethylornithine suppressed the injury-induced increment in spermidine and spermine and microvascular permeability. Putrescine nullified alpha-difluoromethylornithine inhibition and restored microvessel spermidine and spermine and the pathological increase in microvascular permeability. These results indicate that polyamine synthesis is obligatory for blood-brain barrier breakdown. alpha-Difluoromethylornithine may be useful in the treatment of vasogenic brain edema.     

Polyamines are intracellular messengers in the beta-adrenergic regulation of Ca2+ fluxes, [Ca2+]i and membrane transport in rat heart myocytes

The beta-adrenergic agonist 1-isoproterenol (0.1 microM) evokes an acute (less than 5-10 sec) transient increase in the activity of ornithine decarboxylase (ODC), and the levels of polyamines (putrescine, spermidine, spermine) in acutely isolated rat ventricular myocytes. Isoproterenol rapidly (less than 15 sec) increases 45Ca influx and efflux, decreases [Ca2+]i, and stimulates Ca2+-dependent membrane transport (endocytosis, hexose transport, amino acid transport). The beta-adrenergic antagonist propranolol blocks isoproterenol-induced membrane transport. The ODC inhibitor alpha-difluoromethylornithine (DFMO, 5-10 mM) blocks the isoproterenol-evoked increase in ODC activity and polyamine levels and the changes in 45Ca fluxes, [Ca2+]i and membrane transport. Putrescine (0.5-1 mM) replenishes cellular polyamines and reverses the DFMO effect. These data exclude an increase in [Ca2+]i in stimulus-transport coupling, and support the hypothesis that polyamines are messengers in beta-adrenoceptor-mediated regulation of transmembrane Ca2+ fluxes, [Ca2+]i, and Ca2+-dependent membrane transport.     

Testosterone induces a rapid stimulation of endocytosis,amino acid and hexose transport in mouse kidney cortex

Testosterone induced a rapid (<1 min) stimulation of endocytosis, amino acid and hexose transport, measured by the temperature-sensitive uptake of HRP, ¹⁴C-AIB and ³H-DG, in mouse kidney cortex slices. The hormonal increment in uptake persisted for at least 60–120 min, showed time-, energy-, and Na⁺-dependence, and varied with substrate and testosterone concentration. Testosterone was maximally effective at 10^?8 to 10^?7 M. Peroxidase histochemistry indicated that the hormonal increase in HRP uptake is restricted to proximal tubules. Testosterone was more effective than DHT, whereas cyproterone acetate, androsterone and dexamethasone had little or no stimulating effect on this uptake. Kidney slices from androgen-insensitive $\text{tfm}\text{Y}$ mice did not respond to testosterone. The rapid increase in endocytosis, amino acid and hexose transport may represent a direct, receptor-mediated response of the surface membrane of target cells to testosterone.     

Electrophysiologic study of cultured neurons dissociated from spinal cords and dorsal root ganglia of fetal mice

Spontaneously occurring action potentials and postsynaptic potentials were recorded intracellularly from mouse spinal cord (SC) neurons and dorsal root ganglion (DRG) neurons in mixed SC and DRG cell cultures. In some SC cells, excitatory postsynaptic potentials were evoked by electrical stimulation of a nearby SC or DRG cell. SC and DRG neurons had distinguishing morphologic and electrophysiologic properties. SC neurons usually were elliptical or stellate and had several branched processes whereas DRG cells were most commonly round and had on the average only one process, but occasionally 3 or 4. Calculations from cell measurements revealed that SC neurons had less soma surface area and more process surface area than DRG cells, with a similar total surface area for each class. Lower resting membrane potentials were recorded from SC neurons, but when the capability for action potential generation was tested at comparable steady membrane potentials, most SC and less than half of DRG neurons fired repetitively to electrical stimulation. During the depolarizing and repolarizing phases of SC cell action potentials the rates of change of membrane potential were lower than for DRG cells, which had rapidly rising action potentials and a markedly negative afterpotential. An initially delayed repolarization phase was characteristic of the DRG cell action potential. Cell cultures were prepared by trypsin dissociation of spinal cords with attached spinal ganglia from fetuses of 10, 11, 12, 13, 14, and 17 days gestational age. Cell cultures grown on plastic or collagen were studied electrophysiologically at times from 16 to 94 days.     

Androgens regulate mitochondrial cytochrome c oxidase and lysosomal hydrolases in mouse skeletal muscle.

The gastrocnemius, a fast-twitch white muscle, and the soleus, a slow-twitch red muscle, were studied in A/J mice. The specific activities of the lysosomal hydrolases, beta-D-glucuronidase, hexosaminidase, beta-D-galactosidase and arylsulphatase, the inner-mitochondrial-membrane enzyme cytochrome c oxidase, and the outer-mitochondrial-membrane enzyme monoamine oxidase, were greater in the soleus than in the gastrocnemius. The specific activities of the lysosomal hydrolases and cytochrome c oxidase in the gastrocnemius and soleus were substantially higher in male mice than in female mice. Orchiectomy abolished this sex difference. Testosterone increased the activities of the lysosomal hydrolases and cytochrome c oxidase and coincidentally induced muscle hypertrophy and an accretion of protein and RNA, but total DNA remained constant. Monoamine oxidase was unaffected by sex, orchiectomy and testosterone. These findings indicate that endogenous androgens regulate the activity of enzymes associated with lysosomes and the inner mitochondrial membrane, as well as muscle fibre growth in mouse skeletal muscle.     

Substructural specificity and polyvalent carbohydrate recognition by the Entamoeba histolytica and rat hepatic N- acetylgalactosamine/galactose lectins

Both the Entamoeba histolytica lectin, a virulence factor for the causative agent of amebiasis, and the mammalian hepatic lectin bind to N-acetylgalactosamine (GalNAc) and galactose (Gal) nonreducing termini on oligosaccharides, with preference for GalNAc. Polyvalent GalNAc- derivatized neoglycoproteins have >1000-fold enhanced binding affinity for both lectins (Adler,P., Wood,S.J., Lee,Y.C., Lee,R.T., Petri,W.A.,Jr. and Schnaar,R.L.,1995, J. Biol. Chem ., 270, 5164-5171). Substructural specificity studies revealed that the 3-OH and 4-OH groups of GalNAc were required for binding to both lectins, whereas only the E.histolytica lectin required the 6-OH group. Whereas GalNAc binds with 4-fold lower affinity to the E.histolytica lectin than to the mammalian hepatic lectin, galactosamine and N-benzoyl galactosamine bind with higher affinity to the E. histolytica lectin. Therefore, a synthetic scheme for converting polyamine carriers to poly-N-acyl galactosamine derivatives (linked through the galactosamine primary amino group) was developed to test whether such ligands would bind the E.histolytica lectin with high specificity and high affinity. Contrary to expectations, polyvalent derivatives including GalN6lys5, GalN4desmosine, GalN4StarburstTMdendrimer, and GalN8StarburstTMdendrimer demonstrated highly enhanced binding to the mammalian hepatic lectin but little or no enhancement of binding to the E.histolytica lectin. We propose that the mammalian hepatic lectin binds with greatest affinity to GalNAc "miniclusters," which mimic branched termini of N-linked oligosaccharides, whereas the E.histolytica lectin binds most effectively to "maxiclusters," which may mimic more widely spaced GalNAc residues on intestinal mucins.      

Microbiological quality of tomato (<i>Solanum lycopersicum</i> L.) produced under greenhouse conditions in five Municipalities of the State of Mexico

The aim of the current research was to determine tomato (Solanum lycopersicum L.) microbiological quality produced under greenhouse conditions in 5 municipalities of the State of Mexico. Studies were conducted during the 2013 production cycle to know the risks and apply prevention strategies prior to its consumption. A microbiological analysis of samples of irrigation water, soil and 100 tomato fruits variety cid was performed to determine Aerobic Mesophiles, Total Coliforms and Fecal Coliforms. The methodology used were those according to the Official Mexican Standards NOM- 109-SSA1-1994, NOM-110-SSA1-1994, NOM-092-SSA1-1994, NOM-113-SSA1-1994, and the Regulations of the National French Organization for Standardization (AFNOR) NF V08-60, and NOM-093-SSA1-1994, which establish the allowable limits for the study microorganisms. The results showed a zero level of pollution in water and soil samples. For fruits, levels of Aerobic Mesophilic were within the maximum limits permitted by the standards. The municipality of Texcaltitlan showed the highest average for these microorganisms (10083.80 CFU/mL). Huixquilucan showed 2266.84 CFU/mL for Total Coliforms. For Fecal Coliforms, municipalities of Coatepec and Texcaltitlan exceeded the allowed limit.     

A Xenopus tropicalis oligonucleotide microarray works across species using RNA from Xenopus laevis

Microarrays have great potential for the study of developmental biology. As a model system Xenopus is well suited for making the most of this potential. However, Xenopus laevis has undergone a genome wide duplication meaning that most genes are represented by two paralogues. This causes a number of problems. Most importantly the presence of duplicated genes mean that a X. laevis microarray will have less or even half the coverage of a similar sized microarray from the closely related but diploid frog Xenopus tropicalis. However, to date, X. laevis is the most commonly used amphibian system for experimental embryology. Therefore, we have tested if a microarray based on sequences from X. tropicalis will work across species using RNA from X. laevis. We produced a pilot oligonucleotide microarray based on sequences from X. tropicalis. The microarray was used to identify genes whose expression levels changed during early X. tropicalis development. The same assay was then carried out using RNA from X. laevis. The cross species experiments gave similar results to those using X. tropicalis RNA. This was true at the whole microarray level and for individual genes, with most genes giving similar results using RNA from X. laevis and X. tropicalis. Furthermore, the overlap in genes identified between a X. laevis and a X. tropicalis set of experiments was only 12% less than the overlap between two sets of X. tropicalis experiments. Therefore researchers can work with X. laevis and still make use of the advantages offered by X. tropicalis microarrays.