Amino acids derivatives synthesis from nitrogen,carbon and water by electric discharges

Electric discharges between a pair of carbon electrodes were continued for 50 days in a vessel of 5 liters in volume which initially contained nitrogen at a pressure of 15 cm Hg and 200 ml of water. The pressure in the vessel was gradually increased to 60 cm Hg at the end of the run. Gas chromatographic analysis showed that the increase of the pressure mainly results from the production of hydrogen and carbon monoxide. The concentration of ammonia in the aqueous sample was increased to 0.05M in 50 days of the discharge. After hydrolysis, glycine and serine were detected at the concentrations of 3.4×10^–3 M and 0.057×10^–3 M in the final solution, respectively, though glycine was found only at the concentration of 6×10^–6 M before hydrolysis. TLC analysis indicated the presence of hydantoic acid, N-formylglycine, diketopiperazine, and polymers of glycine.     

Effects of endothelin on the renal microcirculation of the split hydronephrotic rat kidney.

We have examined the effects of endothelin (ET) on the renal microcirculation by in vivo microscopy using the model of the split hydronephrotic rat kidney. ET, a potent vasoconstrictor peptide synthesized by vascular endothelial cells, showed marked and long-lasting effects on glomerular blood flow and vessel diameters in various segments of the renal vascular bed. Intravenously applied ET (100 ng/min/kg) increased systemic blood pressure from 123 +/- 7 to 156 +/- 4 mm Hg, decreased glomerular blood flow by 70%, and preferentially constricted larger preglomerular vessels, e.g. the arcuate artery. The competitive leukotriene antagonist FPL55712 significantly attenuated the vasoconstrictor response of the larger vessels. Local ET administration decreased glomerular blood flow in a dose-dependent manner (50% reduction at a concentration of 2.6 +/- 0.7 x 10(-9) M) and constricted smaller vessel segments, e.g. the afferent and efferent arterioles near the glomerulus. The constriction induced by ET was not significantly affected by the Ca2+ channel blocker nitrendipine (2.8 x 10(-6) to 1.1 x 10(-5) M). We conclude that intravenous ET effects are probably mediated by leukotrienes, inducing constriction of larger renal vessels. Locally administered ET acts directly on the renal vasculature, especially on smaller vessels.     

Boronated dipeptide borotrimethylglycylphenylalanine as a potential boron carrier in boron neutron capture therapy for malignant brain tumors.

Takagaki, M., Ono, K., Masunaga, S-I., Kinashi, Y., Oda, Y., Miyatake, S-I., Hashimoto, N., Powell, W., Sood, A. and Spielvogel, B. F. Boronated Dipeptide Borotrimethylglycylphenylalanine as a Potential Boron Carrier in Boron Neutron Capture Therapy for Malignant Brain Tumors. Radiat. Res. 156, 118-122 (2001).A boronated dipeptide, borotrimethylglycylphenylalanine (BGPA), was synthesized as a possible boron carrier for boron neutron capture therapy (BNCT) for malignant brain tumors. In vitro, at equal concentrations of (10)B in the extracellular medium, BGPA had the same effect in BNCT as p-boronophenylalanine (BPA). Boron analysis was carried out using prompt gamma-ray spectrometry and track-etch autoradiography. The tumor:blood and tumor:normal brain (10)B concentration ratios were 8.9 +/- 2.1 and 3.0 +/- 1.2, respectively, in rats bearing intracranial C6 gliosarcomas using alpha-particle track autoradiography. The IC(50), i.e. the dose capable of inhibiting the growth of C6 gliosarcoma cells by 50% after 3 days of incubation, was 5.9 x 10(-3) M BGPA, which is similar to that of 6.4 x 10(-3) M for BPA. The amide bond of BGPA is free from enzymatic attack, since it is protected from hydrolysis by the presence of a boron atom at the alpha-carbon position of glycine. These results suggest promise for the use of this agent for BNCT of malignant brain tumors. Further preclinical studies of BGPA are warranted, since BGPA has advantages over both BPA and BSH.     

Purification and characterization of human seminal plasma aminopeptidase

A 50.4-fold purification of aminopeptidase is achieved by alcohol precipitation, DEAE-cellulose, CM-cellulose and finally Sephadex G-200 chromatography. On polyacrylamide gel electrophoresis of the purified enzyme after molecular sieving on Sephadex G-200, only one band was obtained, suggesting that the enzyme preparation was obtained almost homogeneous by three steps of column chromatography. Aminopeptidase showed highest activity at pH 7.0, using a buffer system, of 70 mM Na-phosphate. The enzyme was found to be active at 40 degrees C, even at 60 degrees C (80% activity), suggesting that the human seminal plasma enzyme is fairly thermostable. Amongst the various aminoacyl derivatives evaluated as substrates in the present study, L-alanine beta-naphthylamide hydrochloride was found to have the highest rate of hydrolysis. Ovalbumin showed effective cleavage in comparison to that of other natural substrates. The Km value for the purified seminal plasma aminopeptidase towards L-alanine beta-naphthylamide hydrochloride was 4 x 10(-4) M. Hg+2 showed highest inhibitory effect than other metal ions tested in the present study. Concentration causing 50% inhibition of the enzyme (I50) by Hg2+ was 4.7 x 10(-6) M. Inhibition by EDTA at 1 mM concentration in the incubation system was higher than by EGTA and sodium azide, suggesting that the enzyme contains a metallo group at the active site. A 50% inhibition of the enzyme by EDTA was obtained at 5.11 x 10(-3) M. The Ackerman and Potter plot for EDTA inhibition suggests that EDTA is a reversible inhibitor of seminal plasma aminopeptidase. A single molecular form of aminopeptidase was found to be present in human seminal plasma as shown by polyacrylamide activity gel electrophoresis.     

Comparison of norepinephrine and serotonin vasoconstriction of the rat isolated testicular subcapsular artery at physiological and elevated transmural pressures.

This laboratory has previously described an in vitro preparation showing that the isolated testicular subcapsular artery of the adult rat has a novel triphasic transmural pressure-diameter myogenic response curve consisting of vasodilatation from 20 to 40 mm Hg, vasoconstriction from 40 to 100 mm Hg, and vasodilatation from 100 to 180 mm Hg, suggesting that the myogenic response of this artery between 40 and 100 mm Hg may have an important role in the autoregulation of the testicular blood supply. In the present studies, a 10-mm length of the adult rat isolated testicular subcapsular artery was cannulated and pressurized by an adjustable-height reservoir. External and internal arterial diameters were measured by a digital filar micrometer eyepiece. Dose-response curves for norepinephrine and serotonin were generated in a double-bath artery chamber at transmural pressures of 70 and 140 mm Hg, using half of the same artery for each pressure. Norepinephrine (3 x 10(-8) to 1 x 10(-5) M) produced a dose-dependent vasoconstriction at 70 mm Hg, with the highest dose causing a 31.4% decrease in lumen cross-sectional area (p < 0.05). Serotonin (3 x 10(-8) to 1 x 10(-6) M) produced a stronger dose-dependent vasoconstriction at 70 mm Hg, with the highest dose causing a 72.7% decrease in lumen cross-sectional area (p < 0.05). In marked contrast, the same concentration of norepinephrine and serotonin were found to have no statistically significant effect on the lumen cross-sectional area of the isolated testicular subcapsular artery at a transmural pressure of 140 mm Hg.(ABSTRACT TRUNCATED AT 250 WORDS)     

Regulation of oxidative phosphorylation in the inner membrane of rat liver mitochondria by calcium ions

The effect of accumulation of Ca2+ at physiological concentrations (10(-8)-10(-6) M) on the rates of ATP synthesis and hydrolysis in rat liver mitochondria was studied. An addition of 5 x 10(-7) M Ca2+ resulted in the maximal rates of synthesis and hydrolysis of ATP. Decrease in the concentration of Ca2+ to 10-8 M or its increase to 5 x 10(-6) M inhibited oxidative phosphorylation and ATP hydrolysis. It was found that the rate of oxidative phosphorylation correlated with the phosphorylation level of a 3.5-kD peptide in the mitochondrial inner membrane on varying the Ca2+ concentration. The possible regulation of oxidative phosphorylation in mitochondria by Ca2+ is discussed.     

膜-生物硝化反应器处理含氨废水效能的研究

研究了膜 生物硝化反应器对含氨废水的处理效能以及分离膜的截留和渗透效能。膜_生物反应器启动迅速 ,在水力停留时间为 1d的情况下 ,反应器最高进水浓度达 80mmol(NH₄⁺-N)·L^-1 ,最高容积负荷达 1 12kg(NH₄⁺ -N)·m^-3·d^-1 ,氨氮去除率保持在 95%以上。试验证明 ,分离膜对微生物有良好的截留作用 ,50天内反应器的污泥浓度从 5g·L^-1 增长到 10g·L^-1 ,分离膜表面附着的生物层则对废水氨氮和亚硝氮有进一步的转化作用。在液位差低于 80cm时 ,提高液位差可增大膜渗透通量 ;液位差超过 80cm后 ,增大液位差的膜渗透通量效应很小 ;其中 ,当液位差为 2 0cm左右时 ,膜通量达 2 . 5 1L·m^-2 ·h^-1 ,阻力最小 [(2 . 6 3× 10^-5)m^-1]。该膜_生物硝化反应器可依靠液位差压力驱动出水 ,无需外加动力。     

An endogenous SCP-related peptide modulates ciliary beating in the gills of a venerid clam, Mercenaria mercenaria

The activities of both the lateral and frontal cilia of Mercenaria mercenaria were unaffected, either by the two endogenous SCP-related peptides AMSFYFPRMamide and YFAFPRQamide, or by FMRFamide (all at 10(-6) M). Dopamine (DA) inhibited the lateral cilia; the mean EC50 was 2 x 10(-6) M. The peptide YFAFPRQamide--but neither AMSFYFPRMamide nor FMRFamide--antagonized the inhibition induced by DA; this effect was dependent on both time and dose. At a DA concentration of 5 x 10(-7) M, the effect of YFAFPRQamide appeared within 20 min and became maximal within 40-60 min; the mean EC50 at these times was 4.7 x 10(-11) M. If the concentration of DA was increased to 10(-6) M, the maximal effect of the peptide was delayed to 50 min, and the mean EC50 increased to 1.1 x 10(-7) M. Particle transport by the frontal cilia was inhibited by 5-hydroxytryptamine (5HT); the mean EC50 was 5.7 x 10(-7) M. Again, only YFAFPRQamide had an antagonistic effect on the 5HT-induced inhibition. At a 5HT concentration of 10(-6) M, the effects of YFAFPRQamide did not appear until 45 min; the mean EC50 was 10(-6) M. When radioimmunoassayed with an SCP antiserum, the elution profile of a gill extract overlapped those of the SCP-related peptides that had previously been identified in extracts of whole animals. These data suggest that all three SCP analogs occur in the gill. Immunohistochemistry of the gill, carried out with a monoclonal antibody raised to SCPB, stained many varicose neuronal fibers. Most of these were associated with the gill musculature, but a sparse innervation of the filaments underlying the cilia was also observed. Some fluorescent nerve cell bodies were also seen in the gill tissue. Our results are consistent with the hypothesis that YFAFPRQamide modulates branchial activities--muscular as well as ciliary--that are associated with feeding.     

Permeability barrier to hydrophilic solutes in Mycobacterium chelonei.

In order to define the permeability barrier to hydrophilic molecules in mycobacteria, we used as a model a smooth, beta-lactamase-producing strain of Mycobacterium chelonei. The rates of hydrolysis of eight cephalosporins by intact and sonicated cells were measured, and the permeability coefficient (P) was calculated from these rates by the method of Zimmermann and Rosselet (W. Zimmermann and A. Rosselet, Antimicrob. Agents Chemother. 12:368-372, 1977). P ranged from (0.9 +/- 0.3) x 10(-8) (benzothienylcephalosporin) to (10 +/- 3.3) x 10(-8) cm/s (cephaloridine); i.e., the P values were lower than those reported for Pseudomonas aeruginosa and Escherichia coli by 1 and 3 orders of magnitude, respectively. The permeability barrier was shown to reduce drastically the stream of drug molecules entering the cell, allowing the rather low level of beta-lactamase (0.1 U/mg of protein with penicillin G) to decrease radically the concentration of the drug at the target; this explains the poor in vitro activities of the beta-lactams against M. chelonei. We also estimated P for small, hydrophilic molecules (glucose, glycerol, glycine, leucine), by studying their uptake kinetics. The values found, ranging from 15 x 10(-8) to 490 x 10(-8) cm/s, were consistent again with a very low permeability of M. chelonei cell wall. The permeation of cephalosporins was not very dependent on the hydrophobicity of the molecules or on the temperature, suggesting a hydrophilic pathway of penetration for these molecules.     

Amplification effect and mechanism of action of ET-1 in U-46619-induced vasoconstriction in pig skin

The aim of this study was to investigate if a low concentration of endothelin-1 (ET-1; 8 x 10(-10) M) may amplify the skin vasoconstrictor effect of other vasoactive substances in the pathogenesis of skin vasospasm. Pig skin flaps (6 x 16 cm) were perfused with Krebs buffer equilibrated with 95% O(2) and 5% CO(2) at 37 degrees C and pH 7.4. Skin perfusion pressure measured by a pressure transducer and skin perfusion assessed by the dermofluorometry technique were used for assessment of skin vasoconstriction. We observed that ET-1 (8 x 10(-10) M) significantly amplified the concentration-dependent (10(-7)-10(-5) M) skin vasoconstrictor effect of norepinephrine. More importantly, we observed for the first time that this low concentration of ET-1 also amplified the concentration-dependent (10(-8)-10(-6) M) skin vasoconstrictor effect of the thromboxane A(2) mimetic U-46619, and this amplification effect of ET-1 was completely blocked by the protein kinase C (PKC) inhibitor chelerythrine (5 x 10(-6) M). Conversely, the PKC activator phorbol 12,13-dibutyrate (10(-7) M) amplified the vasoconstrictor effect of U-46619. Furthermore, the sensitivity of the skin vasculature to the vasoconstrictor effect of extracellular Ca(2+) in U-46619-induced skin vasoconstriction was significantly enhanced in the presence of 8 x 10(-10) M ET-1. Finally, the cyclooxygenase inhibitor indomethacin (5 x 10(-6) M) did not affect the amplification effect of ET-1 on U-46619-induced skin vasoconstriction. We conclude that a low concentration of ET-1 can amplify the skin vasoconstrictor effect of U-46619 independent of endogenous cyclooxygenase products, and the mechanism may involve activation of PKC and increase in sensitivity of the contractile apparatus to Ca(2+) in smooth muscle cells.     

Toxic effects of mercury(II), cadmium(II) and lead(II) porphyrins on Trypanosoma brucei brucei growth

The effects of free mercury(II), cadmium(II) and lead(II) ions and their metalloporphyrin-derivatives on Trypanosoma brucei brucei growth in culture were studied. All experiments were conducted in the dark. IC(50) values on growth obtained in 24-h time-course experiments were 1.5 x 10(-7), 2.4 x 10(-6), 4.4 x 10(-6) and 2.6 x 10(-5) M for mercury(II) porphyrin, cadmium(II) porphyrin, lead(II) porphyrin and free base porphyrin, respectively. While the IC50 values for Hg2+, Cd2+ and Pb2+ were 3.6 x 10(-6), 1.5 x 10(-5) and 1.6 x 10(-5) M, respectively. These results clearly indicate that the toxicity of the metalloporphyrin complexes of mercury(II), cadmium(II) and lead(II) to T. b. brucei parasites was much higher compared to their free metal ions and free base porphyrin at low concentrations. It was also observed after 8 h incubation that the metalloporphyrins were effective in inhibiting the division of the parasites at concentrations >1.25 x 10(-7) M for mercury(II) porphyrin, concentrations >1.2 x 10(-6) M for cadmium(II) and lead(II) porphyrins and at concentrations >3.6 x 10(-6) M for Hg2+ ion. These observations were not detected in samples treated with the free metal ions and the free base porphyrin at the same concentrations. Interestingly, trypanosomes treated with metalloporphyrin complexes displayed different morphological features from those cells treated with free base porphyrin or metal ions. The chemotherapeutic potential of the metalloporphyrins of H2TMPyP for treatment of African trypanosomiasis is discussed.     

Formation of cyanate and carbamyl phosphate by electric discharges of model primitive gas

A mixed gas of nitrogen, carbon dioxide, and hydrogen was discharged over 100 ml of 0.2 M NaHCO3 solution in a 5 liter discharge apparatus which simulates the primitive Earth. The formation of cyanate, which is one of the possible primitive condensing agents, was demonstrated by the detection of [Cu(Py)2] (NCO)2 that was formed by the addition of copper sulfate-pyridine reagent to the solution. In a series of experiments the partial pressures of nitrogen and carbon dioxide in the starting gas were fixed at 10 cm Hg and 20 cm Hg, respectively, whereas that of hydrogen was varied between 5, 10, 15, 20, 25, and 30 cm Hg. The discharges were continued for one week. The rate of appearance of cyanate was strongly dependent upon the partial pressure of hydrogen. The maximum rate of the production of cyanate at the initial stage of the discharge was in the case of 10 cm Hg of hydrogen, in which condition the starting gas is in a predominantly oxidized state. In this case the concentration of cyanate reached about 0.012 M after one day. Another discharge experiment was carried out with 0.2 M phosphate solution, and the production of carbamyl phosphate was demonstrated through the formation of ATP by the incubation of the discharged solution with ADP and carbamyl phosphokinase.     

Comparative study of oestrogenic properties of eight phytoestrogens in MCF7 human breast cancer cells

Previous studies have compared the oestrogenic properties of phytoestrogens in a wide variety of disparate assays. Since not all phytoestrogens have been tested in each assay, this makes inter-study comparisons and ranking oestrogenic potency difficult. In this report, we have compared the oestrogen agonist and antagonist activity of eight phytoestrogens (genistein, daidzein, equol, miroestrol, deoxymiroestrol, 8-prenylnaringenin, coumestrol and resveratrol) in a range of assays all based within the same receptor and cellular context of the MCF7 human breast cancer cell line. The relative binding of each phytoestrogen to oestrogen receptor (ER) of MCF7 cytosol was calculated from the molar excess needed for 50% inhibition of 3H]oestradiol binding (IC50), and was in the order coumestrol (35x)/8-prenylnaringenin (45x)/deoxymiroestrol (50x)>miroestrol (260x)>genistein (1000x)>equol (4000x)>daidzein (not achieved: 40% inhibition at 10(4)-fold molar excess)>resveratrol (not achieved: 10% inhibition at 10(5)-fold molar excess). For cell-based assays, the rank order of potency (estimated in terms of the concentration needed to achieve a response equivalent to 50% of that found with 17beta-oestradiol (IC50)) remained very similar for all the assays whether measuring ligand ability to induce a stably transfected oestrogen-responsive ERE-CAT reporter gene, cell growth in terms of proliferation rate after 7 days or cell growth in terms of saturation density after 14 days. The IC50 values for these three assays in order were for 17beta-oestradiol (1 x 10(-11)M, 1 x 10(-11)M, 2 x 10(-11)M), and in rank order of potency for the phytoestrogens, deoxymiroestrol (1 x 10(-10)M, 3 x 10(-11)M, 2 x 10(-11)M)>miroestrol (3 x 10(-10)M, 2 x 10(-10)M, 8 x 10(-11)M)>8-prenylnaringenin (1 x 10(-9)M, 3 x 10(-10)M, 3 x 10(-10)M)>coumestrol (3 x 10(-8)M, 2 x 10(-8)M, 3 x 10(-8)M)>genistein (4 x 10(-8)M, 2 x 10(-8)M, 1 x 10(-8)M)/equol (1 x 10(-7)M, 3 x 10(-8)M, 2 x 10(-8)M)>daidzein (3 x 10(-7)M, 2 x 10(-7)M, 4 x 10(-8)M)>resveratrol (4 x 10(-6)M, not achieved, not achieved). Despite using the same receptor context of the MCF7 cells, this rank order differed from that determined from receptor binding. The most marked difference was for coumestrol and 8-prenylnaringenin which both displayed a relatively potent ability to displace [3H]oestradiol from cytosolic ER compared with their much lower activity in the cell-based assays. Albeit at varying concentrations, seven of the eight phytoestrogens (all except resveratrol) gave similar maximal responses to that given by 17beta-oestradiol in cell-based assays which makes them full oestrogen agonists. We found no evidence for any oestrogen antagonist action of any of these phytoestrogens at concentrations of up to 10(-6)M on either reporter gene induction or on stimulation of cell growth.     

Mechanical remodeling of small-intestine submucosa small-diameter vascular grafts--a preliminary report

Small-intestine submucosa (SIS) is cell-free, 100-mu-thick collagen derived from the small intestine. It has been used as a vascular graft and has the highly desirable ability to be remodeled to become histologically indistinguishable from native adjacent artery. To date there has been limited reporting of its preimplantation and explant mechanical properties as a vascular graft. In this study, compliance, elastic modulus, and burst pressure were measured on preimplant-tested 5- and 8-mm SIS grafts and two 60-day remodeled grafts. Seven prefabricated grafts were implanted in the carotid (n = 7) in dogs, which were sacrificed after 55-63 days. The animals (n = 4) weighed from 22 to 27 kg. One dog received a unilateral carotid graft, and 3 dogs received bilateral carotid grafts. The fabrication technique employed hand-suturing with either nonresorbable or resorbable sutures. None of the grafts had a patency failure. Angiograms taken at 1 month and just before explantation showed uniform flow and no dilation. At the time of explantation, all carotid grafts were found to be encased in fibrous tissue. The grafts made with nonresorbable sutures showed thicker tissue growth at the suture line compared with those made with the resorbable sutures. Along the suture line, the grafts made with resorbable sutures exhibited a more natural color than those sutured with nonresorbable sutures. When the explanted carotid grafts were slit open, the lumen was white, shiny, and glistening. The grafts sutured with nonresorbable sutures exhibited small areas of fibrin and red blood cells when the suture was within the lumen. The resorbable-sutured grafts did not exhibit this response. The mean compliance (percent diameter increase for a pressure rise from 80 to 120 mm Hg) was on average 4.6% (range, 2.9%-8.6%) for the 5-mm preimplant-tested grafts. For the 8-mm preimplant-tested grafts, the increase in diameter for the same pressure rise was 8.7%, on average (range, 7.2% to 9.5%). For comparison, the small-diameter SIS graft at the time of implantation was about one half as compliant as the adjacent dog carotid artery, about 4 times more compliant than a typical vein graft, and more than 10 times more compliant than synthetic vascular grafts. The compliance measured on two 60-day carotid grafts was 10.5% and 7.2%, respectively. This is midway between the original compliance value and the compliance of a typical canine carotid artery (14%), indicating that mechanical remodeling occurred. The modulus of elasticity (E) increased exponentially with increasing pressure according to E = E0e alpha P, where E0 is the zero-pressure modulus and alpha is the exponent that describes the rate of increase in E with pressure; the unit of measure for variables E, E0, and P is g/cm2. The mean value for E0 was 4106 gm/cm2 (range, 1348-5601). The mean value for alpha was 0.0059 (range, 0.0028-0.0125). At 100 mm Hg, the mean value for E was 8.03 x 10(6) dynes/cm2 (range, 4.95-15.7 x 10(6)). For a 60-day SIS graft implant, the elastic modulus at 100 mm Hg decreased from a high value at implant time to twice that of a typical native canine carotid artery. The mean burst pressure for 5.5-mm grafts was 3517 mm Hg (range, 2069-4654). The burst pressure of the remodeled carotid grafts averaged 5660 mm Hg. The burst pressure for a typical carotid artery is about 5000 mm Hg. The results of this preliminary study complement those of previous SIS-vascular-graft studies and add a new factor, namely that the mechanical properties of the remodeled graft approach those of the vessel it replaces.     

Generation of negative air ions by wheat seedlings in a high voltage electrization of soil

It was shown that plantlets of wheat (Triticum vulgare) are capable of generating negative aeroions during the electrization of soil by high-voltage impulses. Soil electrization was carried out either from the moment of planting of seeds or from the appearance of the first seedlings. The concentration of negative ions was measured in the air at a distance of 50 cm from plants. In both variants, similar growth-related changes in the concentration of negative ions were observed. The generation of negative ions began on day 6 after the planting of seeds and reached a concentration of 380 x 10(3) ion/cm3. During the next three days, this level remained unchanged. On day 10, the generation of negative aeroions increased abruptly; on days 10-14, it was twofold as high as on days 7-9. The level of generation of negative aeroions by plants stimulated from the moment of appearance of plantlets was 5-8% higher than by plants stimulated from the moment of planting. The intensity of generation of negative aeroions upon additional illumination and in full darkness remained unchanged.     

Myometrial cells induce angiogenesis and salvage damaged myocardium

Characteristically, uterine myometrial cells (MCs) are proliferative, inducing angiogenesis within the female reproductive organ. We evaluated whether MCs implanted into myocardium could also induce angiogenesis and restore heart function after injury. MCs were isolated from the adult rat uterus and cultured for three studies: 1) Intracellular VEGF levels were measured in MCs cultured with progesterone (10(-11), 10(-9), and 10(-7) M) (n = 6 tests per group). 2) Blood vessel density was evaluated 8 days after MCs (3 x 10(6) or 6 x 10(6)), smooth muscle cells (SMCs), or endothelial cells (n = 6 rats per group) were injected with matrigel into the subcutaneous tissue of adult rats. 3) MCs, SMCs (5 x 10(6)/rat), or media were injected into a transmural scar 3 wk after cryoinjury in rat hearts (n = 12 rats per group), and heart function, blood vessel density, and myocardial scar size and thickness were evaluated 5 wk later. In study 1, cultured MCs expressed VEGF, with levels significantly (P < 0.05) upregulated by progesterone at an optimal dose of 10(-11) M. In study 2, MCs injected into the subcutaneous tissue with matrigel induced significantly more blood vessels, especially large-diameter vessels, than did SMCs or endothelial cells (P < 0.01 for all groups). This angiogenic effect was greatest (P < 0.01) at higher doses of MCs and was enhanced by progesterone (10(-11) M). In study 3, MCs implanted into the injured myocardium increased blood vessel density at the implant area, reduced scar size, and improved cardiac function relative to SMCs and media. Overall, MCs induced angiogenesis in vitro and in vivo, prevented cardiac remodeling, and improved heart functional recovery after cardiac injury.     

Antioxidant system activation by mercury in Pfaffia glomerata plantlets

Oxidative stress caused by mercury (Hg) was investigated in Pfaffia glomerata plantlets grown in nutrient solution using sand as substrate. Thirty-day-old acclimated plants were treated for 9 days with four Hg levels (0, 1, 25 and 50 μM) in the substrate. Parameters such as growth, tissue Hg concentration, toxicity indicators (δ-aminolevulinic acid dehidratase, δ-ALA-D, activity), oxidative damage markers (TBARS, lipid peroxidation, and H₂O₂ concentration) and enzymatic (superoxide dismutase, SOD, catalase, CAT, and ascorbate peroxidase, APX) and non-enzymatic (non-protein thiols, NPSH, ascorbic acid, AsA, and proline concentration) antioxidants were investigated. Tissue Hg concentration increased with Hg levels. Root and shoot fresh weight and δ-ALA-D activity were significantly decreased at 50 μM Hg, and chlorophyll and carotenoid concentration were not affected. Shoot H₂O₂ concentration increased curvilinearly with Hg levels, whereas lipid peroxidation increased at 25 and 50 μM Hg, respectively, in roots and shoots. SOD activity showed a straight correlation with H₂O₂ concentration, whereas CAT activity increased only in shoots at 1 and 50 μM Hg. Shoot APX activity was either decreased at 1 μM Hg or increased at 50 μM Hg. Conversely, root APX activity was only increased at 1 μM Hg. In general, AsA, NPSH and proline concentrations increased upon addition of Hg, with the exception of proline in roots, which decreased. These changes in enzymatic and non-enzymatic antioxidants had a significant protective effect on P. glomerata plantlets under mild Hg-stressed conditions.     

Air method measurements of apple vessel length distributions with improved apparatus and theory

Studies showing that rootstock dwarfing potential is related to plant hydraulic conductance led to the hypothesis that xylem properties are also related. Vessel length distribution and other properties of apple wood from a series of varieties were measured using the 'air method' in order to test this hypothesis. Apparatus was built to measure and monitor conductivity to air of fresh wood segments of different lengths. Theory for determining vessel length distribution was improved to give a single parameter uni-modal vessel length probability density function. The function, derived by combining the exponential extinction (with extinction coefficient k) of wood conductivity to air (C) as wood length (x) increases (i.e. C=Co exp (-kx)) with the differential double difference formula, is Px=xxk2 exp (-kx), where Px is the fraction of vessels of length x. The main parameter of the distribution, k, was found to be the inverse of the mode of the distribution, i.e. the most common vessel length, Lo. Lo for ten apple rootstock and scion varieties varied from 5.6+/-0.1 cm (+/-SE) for MM.111 to 9.0+/-1.0 for Prunifolia (P <0.05). Average maximum vessel length was approximately 50 cm, and differences were not significant. Effective vessel radii ranged from 14 for Prunifolia to 24.3+/-0.7 micro m for M.26, with standard errors less than 12% of the mean. Specific conductivity of a 15 cm wood segment ranged from 2x109-4) to 1.6+/-0.2x10(-2) dm3 s(-1) kPa(-1) m(-1) for maruba and M.26, respectively, with standard errors up to 63% of the mean. Vessel density at the air entry point ranged from 18+/-3 to 42+/-6 vessels mm-2 for M.26 and MM.106, respectively, with standard errors as high as 89% of the mean. It was concluded that there is no general relationship between the wood properties investigated and rootstock size class, and that plasticity increases from vessel lengths to radii to specific conductivity and vessel densities.     

Tonic regulation of vascular tone by nitric oxide and chloride ions in rat isolated small coronary arteries

We have investigated the involvement of Cl(-) in regulating vascular tone in rat isolated coronary arteries mounted on a small vessel myograph. Mechanical removal of the endothelium or inhibition of nitric oxide (NO) synthase with N(omega)-nitro-L-arginine methyl ester (L-NAME, 10(-4) M) led to contraction of rat coronary arteries, and these contractions were sensitive to nicardipine (10(-6) M). This suggests that release of NO tonically inhibits a contractile mechanism that involves voltage-dependent Ca(2+) channels. In arteries contracted with L-NAME, switching the bathing solution to physiological saline solution with a reduced Cl(-) concentration potentiated the contraction. DIDS (5 x 10(-6)-3 x 10(-4) M) caused relaxation of L-NAME-induced tension (IC(50) = 55 +/- 10 microM), providing evidence for a role of Cl(-). SITS (10(-5)-5 x 10(-4) M) did not affect L-NAME-induced tension, suggesting that DIDS is not acting by inhibition of anion exchange. Mechanical removal of the endothelium led to contraction of arteries, which was sensitive to DIDS (IC(50) = 50 +/- 8 microM) and was not affected by SITS. This study suggests that, in rat coronary arteries, NO tonically suppresses a contractile mechanism that involves a Cl(-) conductance.     

Cyclic AMP Modulates Differentially the Release of Dopamine Induced by Hypoxia and Other Stimuli and Increases Dopamine Synthesis in the Rabbit Carotid Body

We have investigated the effects of different treatments that increase cyclic AMP levels on the in vitro synthesis and release of catecholamines in the rabbit carotid body. We also measured the rate of 45Ca2+ efflux from previously loaded carotid bodies under different conditions. Forskolin produced a dose-dependent increase in the release of [3H]dopamine elicited by a hypoxic stimulus of medium intensity (PO2 = 33 mm Hg) without altering basal [3H]dopamine release (100% O2-equilibrated medium). At a concentration of 5 x 10(-6) M, forskolin increased the release of [3H]dopamine induced by hypoxic stimuli of different intensities; the increase was maximal (498%) at the lowest intensity of hypoxic stimuli (PO2 = 66 mm Hg), averaged 260% for hypoxic stimuli of intermediate intensity and 2 x 10(-4) M cyanide, and was 150% under anoxia. Dibutyryl cyclic AMP (2 mM) and 3-isobutyl-1-methylxanthine (0.5 mM) mimicked forskolin effects under hypoxic stimulation. Forskolin (5 x 10(-6) M) also increased (180%) the release of [3H]dopamine induced by 20% CO2/pH 6.6, 2.5 x 10(-4) M dinitrophenol, and 3 x 10(-5) M ionomycin. Forskolin and 3-isobutyl-1-methylxanthine were without effect on the release of [3H]dopamine elicited by 30 mM extracellular K+. Forskolin (5 x 10(-6) M) augmented significantly the rate of 45Ca2+ efflux induced by hypoxic stimuli (PO2 of 33 and 66 mm Hg) and 2 x 10(-4) M cyanide and showed a tendency to increase (20%) the 45Ca2+ efflux induced by dinitrophenol and low pH and to decrease (21%) the efflux induced by 30 mM K+ without altering the rate of efflux under basal conditions.(ABSTRACT TRUNCATED AT 250 WORDS)