Polyamine Metabolism in the Roots of Phaseolus vulgaris. Interaction of the Inhibitors of Polyamine Biosynthesis with Putrescine in Growth and Polyamine Biosynthesis

The effects of the inhibitors of polyamine biosynthesis, canavanineand -methyl ornithine on growth, the activities of argininedecarboxylase (EC 4.1.1.19 [EC] ) and ornithine decarboxylase (EC4.1.1.17 [EC] ) and on polyamine content were examined in two differentgrowth regions of Phaseolus vulgaris L. cv. Taylor's Horticulturalroots. Separately, in the same manner, in the same bean rootsystem exogenous putrescine effect and the interaction of canavaninewith putrescine were determined. The arginine and ornithine decarboxylase activities found inroot apex were high where cell division activity was highest.Polyamine (putrescine and spermine) content did not correlatewith these activities, but polyamine level was high in the rootbase where cell elongation is the main process. The arginineanalogue, canavanine, inhibited arginine decayboxylase activityand polymine liters. Putrescine partially reversed the canavanineinhibition of root growth as well as arginine decarboxylaseactivity and polyamine content. Similarly -methyl ornithineslightly inhibited the root length and ornithine decarboxylaseactivity in the root apex. Besides, exogenous putrescine didnot effect significantly the endogenous polyamine titers. Theseresults reinforce the growing connection between polyaminesand the rates of cell devision in the roots of bean plants.Separately, arginine decarboxylase is the main enzyme in thebean roots. (Received November 10, 1986; Accepted March 3, 1987)     

Frontal Lobe Hemodynamic Responses to Painful Stimulation: A Potential Brain Marker of Nociception

The purpose of this study was to use functional near-infrared spectroscopy (fNIRS) to examine patterns of both activation and deactivation that occur in the frontal lobe in response to noxious stimuli. The frontal lobe was selected because it has been shown to be activated by noxious stimuli in functional magnetic resonance imaging studies. The brain region is located behind the forehead which is devoid of hair, providing a relative ease of placement for fNIRS probes on this area of the head. Based on functional magnetic resonance imaging studies showing blood-oxygenation-level dependent changes in the frontal lobes, we evaluated functional near-infrared spectroscopy measures in response to two levels of electrical pain in awake, healthy human subjects (n = 10; male = 10). Each subject underwent two recording sessions separated by a 30-minute resting period. Data collected from 7 subjects were analyzed, containing a total of 38/36 low/high intensity pain stimuli for the first recording session and 27/31 pain stimuli for the second session. Our results show that there is a robust and significant deactivation in sections of the frontal cortices. Further development and definition of the specificity and sensitivity of the approach may provide an objective measure of nociceptive activity in the brain that can be easily applied in the surgical setting.     

Polyamine depletion enhances the roscovitine-induced apoptosis through the activation of mitochondria in HCT116 colon carcinoma cells

Small molecule inhibitors of cyclin-dependent kinases (CDKs) show high therapeutic potential in various cancer types which are characterized by the accumulation of transformed cells due to impaired apoptotic machinery. Roscovitine, a CDK inhibitor showed to be a potent apoptotic inducer in several cancer cells. Polyamines, putrescine, spermidine and spermine, are biogenic amines involved in many cellular processes, including apoptosis. In this study, we explored the potential role of polyamines in roscovitine-induced apoptosis in HCT116 colon cancer cells. Roscovitine induced apoptosis by activating mitochondrial pathway caspases and modulating the expression of Bcl-2 family members. Depletion of polyamines by treatment with difluoromethylornithine (DFMO) increased roscovitine-induced apoptosis. Transient silencing of ornithine decarboxylase, polyamine biosynthesis enzyme and special target of DFMO also increased roscovitine-induced apoptosis in HCT116 cells. Interestingly, additional putrescine treatment was found pro-apoptotic due to the presence of non-functional ornithine decarboxylase (ODC). Finally, roscovitine altered polyamine catabolic pathway and led to decrease in putrescine and spermidine levels. Therefore, the metabolic regulation of polyamines may dictate the power of roscovitine induced apoptotic responses in HCT116 colon cancer cells.     

Similarity between contemporary vegetation and plant remains in the surface sediment in Mediterranean lakes

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Synthesis and carbonic anhydrase inhibitory properties of sulfamides structurally related to dopamine

A series of novel sulfamides incorporating the dopamine scaffold were synthesized. Reaction of amines and tert-butyl-alcohol/benzyl alcohol in the presence of chlorosulfonyl isocyanate (CSI) afforded sulfamoyl carbamates, which were converted to the title compounds by treatment with trifluoroacetic acid or by palladium-catalyzed hydrogenolysis. Inhibition of six α-carbonic anhydrases (CAs, EC 4.2.1.1), that is, CA I, CA II, CA VA, CA IX, CA XII and CA XIV, and two β-CAs from Candida glabrata (CgCA) and Mycobacterium tuberculosis (Rv3588) with these sulfamides was investigated. All CA isozymes were inhibited in the low micromolar to nanomolar range by the dopamine sulfamide analogues. K_is were in the range of 0.061–1.822 μM for CA I, 1.47–2.94 nM for CA II, 2.25–3.34 μM for CA VA, 0.041–0.37 μM for CA IX, 0.021–1.52 μM for CA XII, 0.007–0.219 μM for CA XIV, 0.35–5.31 μM for CgCA and 0.465–4.29 μM for Rv3588. The synthesized sulfamides may lead to inhibitors targeting medicinally relevant CA isoforms with potential applications as antiepileptic, antiobesity antitumor agents or anti-infective.     

Reproducing Authigenic Carbonate Precipitation in the Hypersaline Lake Acıgöl (Turkey) with Microbial Cultures

In the present study, laboratory precipitation experiments using similar water chemistry and two different bacterial cultures from Lake Ac?göl sediments, a hypersaline lake in Turkey, were performed to reproduce mineral assemblages similar to those found in the lake. Two different bacterial cultures induce various calcium/magnesium carbonates precipitation under all the experimental conditions (solid vs. liquid): Hydromagnesite, dypingite, huntite, monohydrocalcite, and aragonite. The geochemical program PHREEQC was used to calculate the mineral saturation indexes in the cultures and in lake water. Carbonate mineral assemblages identified in the experiments seem to be independent of the type of microorganisms but rather controlled by the chemical composition and physical conditions of the media. The relative amounts of monohydrocalcite, hydromagnesite, and dypingite are controlled by varying sulfate concentration from 0 to 56 mM. This demonstrates a kinetic effect that could similarly affect the mineral assemblage in the lake. Also the spherical morphology of hydromagnesite points to growth of these minerals under partial inhibition in the brine under high concentrations of ions and organic polymers produced by the microbial communities. As reproduced by the culture experiments, the authigenic carbonate mineral assemblage of Lake Ac?göl most likely results from interplay of ionic composition of the brine and microbial effects.