Effects of 28 days of beta-alanine and creatine monohydrate supplementation on aerobic power,ventilatory and lactate thresholds,and time to exhaustion

Summary. The effect of beta-alanine (β-Ala) alone or in combination with creatine monohydrate (Cr) on aerobic exercise performance is unknown. The purpose of this study was to examine the effects of 4 weeks of β-Ala and Cr supplementation on indices of endurance performance. Fifty-five men (24.5 ± 5.3 yrs) participated in a double-blind, placebo-controlled study and randomly assigned to one of 4 groups; placebo (PL, n = 13), creatine (Cr, n = 12), beta-alanine (β-Ala, n = 14), or beta-alanine plus creatine (CrBA, n = 16). Prior to and following supplementation, participants performed a graded exercise test on a cycle ergometer to determine VO_2peak, time to exhaustion (TTE), and power output, VO₂, and percent VO_2peak associated with VT and LT. No significant group effects were found. However, within groups, a significant time effect was observed for CrBa on 5 of the 8 parameters measured. These data suggest that CrBA may potentially enhance endurance performance.     

The relationship between albumin, other plasma proteins and variables, and age in the acute phase response after liver resection in man

Summary. A large series of plasma albumin (ALB, g/dl) and simultaneous blood and clinical measurements were prospectively performed on 92 liver resection patients, and processed to assess the correlations between ALB, other plasma proteins, additional variables and clinical events. The measurements were performed preoperatively and at postoperative day 1, 3 and 7 in all patients, and subsequently only in those who developed complications or died. In patients who recovered normally ALB was 4.3 ± 0.4 g/dl (mean ± SD) preoperatively, 3.7 ± 0.7 at day 1 and 3, and 3.9 ± 0.4 at day 7. In patients with complications its decrease was more prolonged. In non-survivors it was 3.4 ± 0.4 preoperatively, 3.0 ± 0.4 at day 1, and then decreased further. Regression analysis showed direct correlations between ALB and pseudo-cholinesterase (CHE, U/l, nv 5300-13000), cholesterol (CHOL, mg/dl), iron binding capacity (IBC, mg/dl), prothrombin activity (PA, % of standard reference) and fibrinogen, an inverse correlation with blood urea nitrogen (BUN, mg/dl) for any given creatinine level (CREAT, mg/dl), and weaker direct correlations with hematocrit, other variables and dose of exogenous albumin. An inverse relationship found between ALB and age (AGE, years) became postoperatively (POSTOP) also a function of outcome, showing larger age-related decreases in ALB associated with complications (COMPL: sepsis, liver insufficiency) or death (DEATH). Main overall correlations: CHE = 287.4(2.014)^ALB, r = 0.73; CHOL = 16.5(1.610)^ALB (1.001)^ALKPH, r = 0.71; IBC = 68.6(1.391)^ALB, r = 0.64; PA = 13.8 + 16.0(ALB), r = 0.51; BUN = 21.3 + 20.2(CREAT) – 6.2(ALB), r = 0.91; ALB = 5.0–0.013(AGE) – {0.5 + 0.003(AGE) _COMPL + 0.012(AGE) _DEATH } _POSTOP , r = 0.74 [p < 0.001 for each regression and each coefficient; ALKPH = alkaline phosphatase, U/l, nv 98-279, independent determinant of CHOL; discontinuous variables in italics label the change in regression slope or intercept associated with the corresponding condition]. These results suggest that altered albumin synthesis (or altered synthesis unable to compensate for albumin loss, catabolism or redistribution) is an important determinant of hypoalbuminemia after hepatectomy. The correlations with age and postoperative outcome support the concept that hypoalbuminemia is a marker of pathophysiologic frailty associated with increasing age, and amplified by the challenges of postoperative illness.     

Effects of β-alanine supplementation on the onset of neuromuscular fatigue and ventilatory threshold in women

Summary. This study examined the effects of 28 days of β-alanine supplementation on the physical working capacity at fatigue threshold (PWC_FT), ventilatory threshold (VT), maximal oxygen consumption ( O_2-MAX), and time-to-exhaustion (TTE) in women. Twenty-two women (age ± SD 27.4 ± 6.1 yrs) participated and were randomly assigned to either the β-alanine (CarnoSyn™) or Placebo (PL) group. Before (pre) and after (post) the supplementation period, participants performed a continuous, incremental cycle ergometry test to exhaustion to determine the PWC_FT, VT, O_2-MAX, and TTE. There was a 13.9, 12.6 and 2.5% increase (p < 0.05) in VT, PWC_FT, and TTE, respectively, for the β-alanine group, with no changes in the PL (p > 0.05). There were no changes for O_2-MAX (p > 0.05) in either group. Results of this study indicate that β-alanine supplementation delays the onset of neuromuscular fatigue (PWC_FT) and the ventilatory threshold (VT) at submaximal workloads, and increase in TTE during maximal cycle ergometry performance. However, β-alanine supplementation did not affect maximal aerobic power ( O_2-MAX). In conclusion, β-alanine supplementation appears to improve submaximal cycle ergometry performance and TTE in young women, perhaps as a result of an increased buffering capacity due to elevated muscle carnosine concentrations.     

Polyamine contents in current foods: a basis for polyamine reduced diet and a study of its long term observance and tolerance in prostate carcinoma patients

Summary. Our aim was to develop a liquid chromatography and electrospray ionization tandem mass spectrometry (LCMS²) method to measure free amino acid (FAA) and dipeptide (DP) concentrations in biological fluids. We synthesized chloroformate derivatives of FAA and DP, identified the major precursor ions and used LCMS² to obtain the most intense product ions. Using serial dilutions of unlabeled and labeled standards ([²H₃]-L-Dopa, homoarginine, homophenylalanine, [¹⁵N]-Glutamine and [²H₃]-methionine), we observed linear relationships in MS response that we used to calculate the amounts of FAA and DP in biological samples. This method is sensitive with a limit of detection (LOD) for most of the FAAs and DPs tested in the 0.05–1 pmol range and is linear over 3–5 orders of magnitude when many metabolites were measured simultaneously. Reproducibility and between run or daily variations were <10% for most FAAs and DPs. We applied this method to human samples and quantitatively measured 21 FAAs and 2 DPs in 200 μl CSF, 31 FAAs and 6 DPs in 100 μl plasma, and 23 FAAs and 5 DPs in 200 μl urine. These data demonstrate the potential for using LCMS² to discover changes in FAA and DP metabolic pathways that occur during disease pathogenesis.     

Effects of D-amino acids on lipoperoxidation in rat liver and kidney mitochondria

Summary. The effects of the amino acids D-ser, D-asp, and D-ala on lipoperoxidation under conditions of hypertension, alcoholism, and ammonemia in rat liver and kidney mitochondria were studied. Under normal conditions, D-alanine increased in 54% free radicals production in liver mitochondria (p < 0.05). The D-amino acids had no effect on kidney mitochondria. D-ser and D-ala increased lipoperoxidation in spontaneously hypertensive rats (SHR) as compared with their normotensive genetic control Wistar-Kyoto (WKY) rats (p < 0.05). During hypertension and in oxidative stress in the presence of calcium, only D-ala produced 46% and 29% free radicals in liver and kidney mitochondria (p < 0.05), respectively. During chronic alcoholism, D-ser increased lipoperoxidation in 80% in kidney mitochondria (p < 0.05), as compared to control. During ammonemia, D-ser produced 41% free radicals.     

Abnormal changes of plasma acute phase proteins in schizophrenia and the relation between schizophrenia and haptoglobin (Hp) gene

Summary. In this study we focused on detecting schizophrenia related changes of plasma proteins using proteomic technology and examining the relation between schizophrenia and haptoglobin (Hp) genotype. We investigated plasma proteins from schizophrenic subjects (n = 42) and healthy controls (n = 46) by two-dimensional gel electrophoresis (2-DE) in combination with mass spectrometry. To further reveal the genetic relationship between acute phase proteins (APPs) and schizophrenia disease, we tested Hp α1/Hp α2 (Hp 1/2) polymorphism and two single nucleotide polymorphisms (SNPs) of Hp, rs2070937 and rs5473, for associations with schizophrenia in the Chinese Han population. With the relatively high number of samples for 2-DE work, we found that four proteins in the family of positive APPs were all up-regulated in patients. In genetic association study, we found significant associations existing between schizophrenia and Hp polymorphisms, Hp 1/2 and rs2070937 variants. Schizophrenia is accompanied by both an altered expression of Hp protein and a different genotype distribution of Hp gene, demonstrating that Hp is associated with schizophrenia. The results from proteomic and genomic aspects both indicate that acute phase reaction is likely to be an aetiological agent in the pathophysiology of schizophrenia, but not just an accompanying symptom. The positive APPs are schizophrenic related proteins, with the highly concordant results on four positive APPs. The first two authors contributed equally.     

Characterization of pectin methyltransferase from soybean hypocotyls

Pectin methyltransferase (PMT) catalyzing the transfer of the methyl group from S-adenosyl-L-methionine (SAM) to the C-6 carboxyl group of galactosyluronic acid residues in pectin was found in a membrane preparation of etiolated hypocotyls from 6-d-old soybean (Glycinemax Merr.). The enzyme was maximally active at pH 6.8 and 35–40 °C, and required 0.5% (w/v) Triton X-100. The incorporation of the methyl group was significantly enhanced by addition of a pectin with a low (22%) degree of methyl-esterification (DE) as exogenous acceptor substrate. The apparent Michaelis constants for SAM and the pectin (DE22) were 0.23 mM and 66 μg · ml⁻¹, respectively. Attachment of the methyl group to the carboxyl group of the pectin via ester linkage was confirmed by analyzing radiolabeled product from incubation of the enzyme with [¹⁴C]methyl SAM and the acceptor pectin. Size-exclusion chromatography showed that both enzymatic hydrolysis with a pectin methylesterase and a mild alkali treatment (saponification) led to the release of radioactive methanol from the product. Enzymatic hydrolysis of the product with an endopolygalacturonase degraded it into small pectic fragments with low relative molecular mass, which also supports the idea that the methyl group is incorporated into the pectin. The soybean hypocotyls were fractionated into their cell wall components by successive extraction with water, EDTA, and alkali treatment. Among the resulting polysaccharide fractions, high PMT activity was observed when a de-esterified polysaccharide derived from the EDTA-soluble fraction (the pectic fraction) was added as an alternative acceptor substrate, indicating that the enzyme may be responsible for producing methyl-esterified pectin in vivo. Received: 10 September 1999 / Accepted: 11 October 1999     

Peptaibiomics: an advanced, rapid and selective analysis of peptaibiotics/peptaibols by SPE/LC-ES-MS

Summary. “Proteomics” and “peptidomics” are used as technical terms to define the analysis and study of all proteins and peptides expressed in an organism or tissue. In analogy we propose the name peptaibiomics for the analysis of a group of fungal peptide antibiotics (peptaibiotics) containing the characteristic amino acid Aib (α-aminoisobutyric acid). In analogy to the peptidome the complete expression of peptaibiotics by fungal multienzyme complexes should be named the peptaibiome. Peptaibiotics are defined as peptides containing Aib and exerting a variety of bioactivities. They comprise the sub-groups of N-acetylated peptaibols, characterized also by a C-terminal amide-linked 2-amino alcohol, and lipopeptaibols having in place of an acetyl group a lipophilic fatty acid acyl group. Furthermore, lipoaminopeptides are also known with long-chain fatty acid on the N-termini, a lipoamino acid in position three and a strongly basic secondary or tertiary amine form a subgroup of mixed forms which could not be integrated in one of these three previously mentioned groups. Here we present a specific and rapid screening method on the peptaibiome applicable directly onto filamentous fungi cultured in a single Petri dish. The method comprises solid-phase extraction (SPE) of peptaibiotics followed by on-line reversed-phase HPLC coupled to an ion trap electrospray tandem mass spectrometer (ES-MS). The presence of these peptides is indicated by characteristic mass differences of Δm = 85.1 Da representing Aib-residues which can be observed in the b-series of acylium fragment ions resulting from ES-MS. Partial sequences can be deduced from the data and compared with structures compiled in electronic peptaibol data bases. The judgement is possible whether or not structures are novel, already known or related to known structures. Suitability of the method is demonstrated with the analysis of strains of Trichoderma and its teleomorph Hypocrea. New sequences of peptaibiotics are presented and those being related to established 10- to 18-residue peptaibols trichovirin, trichogin and trichotoxin, which have been described in the literature.     

Non-sufficient cell cycle control as possible clue for the resistance of human malignant glioma cells to clinically relevant treatment conditions

Summary. Objectives. Human gliomas have a catastrophic prognosis with a median survival in the range of one year even after therapeutic treatment. Relatively high resistance towards apoptotic stimuli is the characteristic feature of malignant gliomas. Since cell cycle control has been shown to be the key mechanism controlling both apoptosis and proliferation, this study focuses on DNA damage analysis and protein expression patterns of essential cell cycle regulators P53 and P21^waf1/cip1 in glioma under clinically relevant therapeutic conditions. Material and methods. U87MG cell line, characterised by wild p53-phenotype relevant for the majority of primary malignant glioblastomas, was used. Glioma cells underwent either irradiation or temozolomide treatment alone, or combined radio/chemo treatment. DNA damage was analysed by the “Comet Assay”. Expression rates of target proteins were analysed using “Western-Blot” technique. Results and conclusions. “Comet Assay” demonstrated extensive DNA damage caused by temozolomide treatment alone and in combination with irradiation, correlating well with the low survival rate observed under these treatment conditions. In contrast, irradiation alone resulted in a relatively low DNA damage, correlating well with a high survival rate and indicating a poor therapeutic efficiency of irradiation alone. Unusually low up-regulation of P53 and P21^waf1/cip1 expression patterns was produced by the hereby tested stressful conditions. A deficit in cell cycle control might be the clue to the high resistance of malignant glioma cells to established therapeutic approaches.     

The peptides of α-aminosuberic acid I New intermediates for synthetic studies

Summary. The paper describes the synthesis of α-aminosuberic acid derivatives suitable for the synthesis of peptides. These include Z-, Boc- and Fmoc-protection on the α-amino group, benzyl ester, Boc-hydrazide and Z-hydrazide as well as the free carboxylic function in the side chain, and methyl ester, benzyl ester or free α-carboxylic group. Their use is demonstrated on the synthesis of the respective derivatives of Asu-Val-Leu. The enzyme catalyzed reaction was succesfully used both as a route to L-Asu from the D,L-compound as well as for the direct synthesis of the optically active tripeptide derivative from the Z-D,L-Asu-OH. Received February 5, 1999     

The influence of mandibular implant-retained overdentures in masticatory efficiency

doi: 10.1111/j.1741‐2358.2011.00539.x The influence of mandibular implant‐retained overdentures in masticatory efficiency Objective: To evaluate the masticatory efficiency of patients rehabilitated with conventional dentures (CDs) or implant‐retained mandibular overdentures. Background: Despite the evident benefits of implants on mastication as assessed by subjective patient‐based outcomes, the extent of implant overdenture treatment effect on food comminution is not well established. Materials and methods: A randomised clinical trial was carried out with 29 completely edentulous patients divided into two groups. The first group was rehabilitated with a mandibular overdenture retained by two splinted implants with bar‐clip system, while the second group was rehabilitated with a mandibular CD. Both groups also were rehabilitated with maxillary CDs. Masticatory efficiency and patient satisfaction were assessed 3 months after denture insertion. Masticatory efficiency was evaluated through the colorimetric method with the beads as the artificial test‐food. Comparisons for masticatory efficiency and patient satisfaction were performed using Student’s t‐test (α = 0.05). Results: No significant statistical difference was found for masticatory efficiency (p = 0.198). Patient overall satisfaction was significantly higher for the mandibular overdenture (p < 0.001). In addition, mandibular overdenture patients were significantly more satisfied with chewing experience (p < 0.05) and retention of the lower denture (p < 0.005). Conclusion: The results of this study suggest that mandibular overdenture significantly improves chewing experience, although limited effect on masticatory efficiency has been observed.     

Turing instabilities in general systems

We present necessary and sufficient conditions on the stability matrix of a general n(≥2)-dimensional reaction-diffusion system which guarantee that its uniform steady state can undergo a Turing bifurcation. The necessary (kinetic) condition, requiring that the system be composed of an unstable (or activator) and a stable (or inhibitor) subsystem, and the sufficient condition of sufficiently rapid inhibitor diffusion relative to the activator subsystem are established in three theorems which form the core of our results. Given the possibility that the unstable (activator) subsystem involves several species (dimensions), we present a classification of the analytically deduced Turing bifurcations into p (1 ≤p≤ (n− 1)) different classes. For n = 3 dimensions we illustrate numerically that two types of steady Turing pattern arise in one spatial dimension in a generic reaction-diffusion system. The results confirm the validity of an earlier conjecture [12] and they also characterise the class of so-called strongly stable matrices for which only necessary conditions have been known before [23, 24]. One of the main consequences of the present work is that biological morphogens, which have so far been expected to be single chemical species [1–9], may instead be composed of two or more interacting species forming an unstable subsystem. Received: 21 September 1999 / Revised version: 21 June 2000 / Published online: 24 November 2000     

L-NAME administration prevents the inhibition of nucleotide hydrolysis by rat blood serum subjected to hyperargininemia

Summary. The main objective of the present study was to evaluate the in vivo and in vitro effect of Arg on serum nucleotide hydrolysis. The action of N^ω-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide synthase, on the effects produced by Arg was also examined. Sixty-day-old rats were treated with a single or a triple (with an interval of 1 h between each injection) intraperitoneal injection of saline (group I), Arg (0.8 g/kg) (group II), L-NAME (2.0 mg/kg or 20 mg/kg) (group III) or Arg (0.8 g/kg) plus L-NAME (2.0 mg/kg or 20 mg/kg) (group IV) and were killed 1 h later. The present results show that a triple Arg administration decreased ATP, ADP and AMP hydrolysis. Simultaneous injection of L-NAME (20 mg/kg) prevented such effects. Arg in vitro did not alter nucleotide hydrolysis. It is suggested that in vivo Arg administration reduces nucleotide hydrolysis in rat serum, probably through nitric oxide or/and peroxynitrite formation. Both are first authors.     

Influence of pegylated interferon-α therapy on plasma levels of citrulline and arginine in melanoma patients

Summary. The aim of this study was to evaluate the effect of pegylated interferon-alpha (PEG-IFN-α) on the plasma citrulline/arginine ratio, regarded as an index of nitric oxide (NO) synthesis, in patients with high-risk melanoma. Forty patients were randomly assigned to either PEG-IFN-α treatment (n = 22) or to observation only (control group, n = 18). The treatment group received 6 μg PEG-IFN-α/kg once a week during 8 weeks, followed by a maintenance dose of 3 μg/kg/wk. Blood was collected at different time points, plasma concentrations of citrulline and arginine were measured and the ratio of citrulline/arginine was calculated. Patients treated with PEG-IFN-α showed a significant decrease in the concentrations of citrulline and in the citrulline/arginine ratio during the whole study period, both compared to baseline values and to the control group. The data suggest that therapy with PEG-IFN-α results in a marked decrease in the synthesis of NO in melanoma patients.     

Application of several types of substrates to ficin-catalyzed peptide synthesis

Summary. The capability of ficin, a cystine protease, to form peptide bonds was investigated using several types of N-Boc-amino acid phenyl and naphthyl esters as acyl donor components. Enzyme-catalyzed peptide synthesis was carried out under optimized reaction conditions of pH, acyl acceptor concentration and selection of the best yield organic solvent. It used a condensation of N-Boc-Ala-OpGu and Ala-pNA as a model reaction. The products were obtained in 72–96% yield using 10 different substrates, within a few minutes of reaction time. Authors’ address: Prof. Haruo Sekizaki, Faculty of Pharmaceutical Sciences, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido 061-0293, Japan     

In vitro biosynthesis of 1,4-β-galactan attached to rhamnogalacturonan I

 The biosynthesis of galactan was investigated using microsomal membranes isolated from suspension-cultured cells of potato (Solanum tuberosum L. var. AZY). Incubation of the microsomal membranes in the presence of UDP-[¹⁴C]galactose resulted in a radioactive product insoluble in 70% methanol. The product released only [¹⁴C]galactose upon acid hydrolysis. Treatment of the product with Aspergillus niger endo-1,4-β-galactanase released 65–70% of the radioactivity to a 70%-methanol-soluble fraction. To a minor extent, [¹⁴C]galactose was also incorporated into proteins, however these galactoproteins were not a substrate for Aspergillus niger endo-1,4-β-galactanase. Thus, the majority of the ¹⁴C-labelled product was 1,4-β-galactan. Compounds released by the endo-1,4-β-galactanase treatment were mainly [¹⁴C]galactose and [¹⁴C]galactobiose, indicating that the synthesized 1,4-β-galactan was longer than a trimer. In vitro synthesis of 1,4-β-galactan was most active with 6-d-old cells, which are in the middle of the linear growth phase. The optimal synthesis occurred at pH 6.0 in the presence of 7.5 mM Mn²⁺. Aspergillus aculeatus rhamnogalacturonase A digested at least 50% of the labelled product to smaller fragments of approx. 14 kDa, suggesting that the synthesized [¹⁴C]galactan was attached to the endogenous rhamnogalacturonan I. When rhamnogalacturonase A digests of the labelled product were subsequently treated with endo-1,4-β-galactanase, radioactivity was not only found as [¹⁴C]galactose or [¹⁴C]galactobiose but also as larger fragments. The larger fragments were likely the [¹⁴C]galactose or [¹⁴C]galactobiose still attached to the rhamnogalacturonan backbone since treatment with β-galactosidase together with endo-1,4-β-galactanase digested all radioactivity to the fraction eluting as [¹⁴C]galactose. The data indicate that the majority of the [¹⁴C]galactan was attached directly to the rhamnose residues in rhamnogalacturonan I. Thus, isolated microsomal membranes contain enzyme activities to both initiate and elongate 1,4-β-galactan sidechains in the endogenous pectic rhamnogalacturonan I. Received: 24 June 1999 / Accepted: 30 August 1999     

Diuretic potential of energy drinks

Summary. Recent literature suggests that both caffeine and taurine can induce diuresis and natriuresis in rat and man. Although they act via different cellular mechanisms, their diuretic actions might be additive. This is of considerable interest, as several commercially available energy drinks contain both substances. In this study we examined the possible diuretic effects of caffeine and taurine in a cross-over-design in which 12 healthy male volunteers received each of 4 different test drinks (750 ml of energy drink containing 240 mg caffeine and 3 g taurine, the three other test drinks either lacked caffeine, taurine or both) after restraining from fluids for 12 h. Mixed model analyses demonstrated that urinary output and natriuresis were significantly increased by caffeine (mean differences 243 ml and 27 mmol; both p < 0.001) and that there were no such effects of taurine (mean differences 59 ml and −4 mmol). Additionally, urinary osmolarity at baseline was significantly related to the urinary output (p < 0.001). Urine osmolarity values at baseline and in the 6 h urine collection did not differ significantly between treatments. Taken together, our study demonstrates that diuretic and natriuretic effects of the tested energy drink were largely mediated by caffeine. Taurine played no significant role in the fluid balance in moderately dehydrated healthy young consumers. Consequently, the diuretic potential of energy drinks will not differ significantly from other caffeine containing beverages.     

Microinjection of heme oxygenase genes rescues phytochrome-chromophore-deficient mutants of the moss Ceratodon purpureus

 In protonemal tip cells of the moss Ceratodon purpureus (Hedw.) Brid., phototropism and chlorophyll accumulation are regulated by the photoreceptor phytochrome. The mutant ptr116 lacks both responses as a result of a defect in the biosynthesis of phytochromobilin, the chromophore of phytochrome, at the point of biliverdin formation. The rescue of the phototropic response and of chlorophyll synthesis were tested by injecting different substances into tip cells of ptr116. Microinjection was first optimised with the use of fluorescent dyes and an expression plasmid containing a green fluorescent protein (GFP) gene. Injected phycocyanobilin, which substitutes for phytochromobilin, rescued both the phototropic response and light-induced chlorophyll accumulation in ptr116. The same results were obtained when expression plasmids with heme oxygenase genes of rat (HO-1) and Arabidopsis thaliana (L.) Heynh. (HY1) were injected. Heme oxygenase catalyses the conversion of heme into biliverdin. Whereas HY1 has a plastid target sequence and is presumably transferred to plastids, HO-1 is proposed to be cytosolic. The data show that ptr116 lacks heme oxygenase enzyme activity and indicate that heme oxygenases of various origin are active in Ceratodon bilin synthesis. In addition, it can be inferred from the data that the intracellular localisation of the expressed heme oxygenase is not important since the plastid enzyme can be replaced by a cytosolic one. Received: 8 March 1999 / Accepted: 30 July 1999     

Effects of testosterone and 17, β– estradiol on the polyamine metabolism in cultivated normal rat kidney epithelial cells

Summary. Ornithine decarboxylase (ODC) and diamine oxidase (DAO) are important enzymes involved in the metabolism of polyamines (putrescine, spermidine and spermine). The influence of testosterone (T) and 17, β– estradiol (E₂) on the activity of ODC and DAO was examined in cultivated normal rat kidney (NRK) epithelial cells. The results showed an increase in enzyme activities 4 hours or 12 hours after hormonal treatment. Both T and E₂ led to a significant increase (1.6-fold) in ODC protein level as compared to the controls. Cellular concentration of spermidine and spermine increased (2.2- and 2.6-fold respectively) 4 hours after T addition. A higher levels in concentrations of putrescine (1.4-fold) and spermine (1.5-fold) 12 hours after E₂ treatment were observed. These results suggest that the biosynthesis and terminal oxidation of the polyamines in NRK epithelial cells are androgen- and estrogen-mediated and depend on the hormonal sensitivity of the cells. Received April 5, 1999, Accepted December 20, 1999     

Abscisic acid-induced changes in inositol metabolism in Spirodela polyrrhiza

 In response to abscisic acid (ABA), the duckweed Spirodela polyrrhiza (L.) activates a developmental pathway that culminates in the formation of dormant structures known as turions. Levels of the mRNA encoding d-myo-inositol-3-phosphate synthase (EC.5.5.1.4) which converts glucose-6-phosphate to inositol-3-phosphate, increase early in response to ABA. In order to understand the role of this enzyme in turion formation, we have investigated changes in inositol metabolism in ABA-treated plants. Here, we show that ABA-treatment leads to a 3-fold increase in free inositol, which peaks 2 d after treatment. This increase is followed by sequential increases in inositol phosphates and in accumulation of inositol hexakisphosphate (InsP₆), in particular. In addition, we observed an early increase in a novel inositol bisphosphate which is not directly on the pathway to InsP₆. In control plants, we observed synthesis and turnover of both inositol pentakisphosphate and InsP₆. Two compounds more polar than InsP₆ (diphosphoinositol polyphosphates) were present in both ABA-treated and control plants. Together, this suggests that the role of InsP₆ in plants may be more complex than simply that of a storage compound during dormancy. Received: 10 January 2000 / Accepted: 25 February 2000