Effect of hormone replacement therapy on the elemental contents of uterine tissue

For the past years, different therapies based on steroid hormone supplementation or modulators of estrogen receptors have been used after menopause to prevent or manage osteoporosis. Although these treatments seem to be beneficial, they have some negative effects in the uterus and breast. The objective of this study was to assess variations for the concentrations of K, Ca, Mn, Fe, Cu, Zn, and Se in uterine tissue of Wistar rats. Ovriectomized rats were subjected to estrogen, progesterone, raloxifene, and tibolone supplementation and compared with nonovariectomized control animals. Elemental contents determined by the particle-induced X-ray emission (PIXE) technique revealed major alterations in Fe, Ca, Mn, and Se in the uterus of ovariectomized rats relative to control animals. After ovariectomy, a significant increase in Ca and Fe and a significant decrease in Mn and Se contents were determined in the uterus. For the ovariectomized groups in which animals, received raloxifene, tibolone, estrogen, and estrogen combined with progesterone supplementation, an overall recovery in Mn, Fe, and Se contents was verified. Elemental concentration in the progesterone-supplemented group did not significantly differ from ovariectomized animals receiving placebo. The alterations found for ovariectomized animals receiving placebo and progesterone suggest tissue impairment and trace element imbalance, contrasting with the remaining supplemented groups where an enhancement of tissue activity might justify similar concentration levels relative to controls, because most of the elemental contents altered after ovariectomy.     

Synthesis and pharmacological evaluation of prenylated and benzylated pterocarpans against snake venom

Edunol (3), a pterocarpan isolated from Harpalyce brasiliana, a plant used in the northeast of Brazil against snakebites, was obtained by synthesis and showed antimyotoxic, antiproteolytic and PLA2 inhibitor properties. These proprieties could be improved through the synthesis of a bioisoster (5), where the prenyl group was replaced by the benzyl group.     

The effect of cations on the amidase activity of human tissue kallikrein: 1-linear competitive inhibition by sodium, potassium, calcium and magnesium. 2-linear mixed inhibition by aluminium

Hydrolysis of D-valyl-L-leucyl-L-arginine p-nitroanilide by human tissue kallikrein (hK1) was studied in the absence and in the presence of increasing concentrations of the following chloride salts: sodium, potassium, calcium, magnesium and aluminium. The data indicate that the inhibition of hK1 by sodium, potassium, calcium and magnesium is linear competitive and that divalent cations are more potent inhibitors of hK1 than univalent cations. However the inhibition of hK1 by aluminium cation is linear mixed, with the cation being able to bind to both the free enzyme and the ES complex. This cation was the best hK1 inhibitor. Aluminium is not a physiological cation, but is a known neurotoxicant for animals and humans. The neurotoxic actions of aluminium may relate to neuro-degenerative diseases.     

DISCO--a general computer program for the computation of acid dissociation constants of polyprotic molecules in water and biological fluids,from nuclear magnetic resonance data: application to polyamines

A new computer program, DISCO, running under Windows, has been developed under the project CSA98P22 falling within the Competitive Support Activities initiative launched within the EU 4th Framework Programme. DISCO allows the calculation of the stepwise acid dissociation constants of polyprotic molecules in water and in complex media (i.e., biofluids, etc.) from nuclear magnetic resonance (NMR) data (chemical shifts) by means of two derivative-free methods: Pit-mapping and Simplex. DISCO performances were tested using simulated-unaffected by experimental error-data sets, for systems having up to seven equilibrium constants and experimental NMR data of spermine, 6-monofluorospermine, and 6,6-difluorospermine, dissolved in D(2)O and in physiological solution (D(2)O/NaCl). Results demonstrated that (i) DISCO enables the determination of pK(A) values with high precision even when small-sized raw data sets are employed, when chemical shifts are measured with low precision (the usual condition in biofluids due to the impossibility to obtain narrow line shape), and when the guess solution, necessary as an initial step of the mathematical iterative process, is fixed within a large interval of variation; (ii) DISCO always converges to the root; (iii) DISCO permits the calculation of pK(A) values which lie within the observed pH range, independent of the narrowness of the pH range.     

Determination of dissociation constants of (4RS)-[4-carboxy-5,8,11-tris(carboxymethyl)-1-phenyl-2-oxa-5,8,11-triazatridecan-13-oic acid] in water and biological fluids by means of nuclear magnetic resonance spectroscopy and the DISCO software package

The pK(A) values of (4RS)-[4-carboxy-5,8,11-tris(carboxymethyl)-1-phenyl-2-oxa-5,8,11-triazatridecan-13-oic acid] (BOPTA), a polyprotic molecule whose gadolinium complex is an important magnetic resonance imaging contrast agent for clinical use, have been determined in water, in physiologic solution (PS), in serum (S), and in cerebrospinal fluid (CSF), by means of 13C nuclear magnetic resonance spectroscopy data processed by a dedicated software package called DISCO. The aim of this study was to supply the BOPTA pK(A) values in media very similar to the in vivo environment and, consequently, to get a picture of the in vivo behavior of its Gd complex, whose thermodynamic stability is directly linked to the pK(A) values. The pK(A) values appeared to be almost equal both in D(2)O and in PS, while pK(1) and pK(5) values in CSF differ a little. In S, only pK(2) and pK(3) were calculated due to the narrow pH range used for data collection. However, these pK(A) values were found equal to those in the other media. These results represent the first direct spectroscopic evidence of a substantial invariability of BOPTA behavior in different media and they justify the extrapolation to biological fluids of the data obtained in water. The values also confirmed the high-quality performance of DISCO in calculating pK(A) values of polyprotic molecules in complex media.     

Small-Scale Distribution of Bacteria,Enzymatic Activities,and Organic Matter in Coastal Sediments

apd: 9 February 2001     

Primate Population Densities and Sizes in Atlantic Forest Remnants of Northern Espírito Santo,Brazil

We surveyed primates in seven fragments of Atlantic forest ranging from 210 to 24,250 ha in Espírito Santo, southeastern Brazil. The objective was to assess their population densities and fragment-specific population sizes in order to discuss the survival of primates in this highly fragmented landscape. We used line-transect sampling for censusing primates and estimated densities via DISTANCE program. Alouatta fusca, Cebus apella, Callicebus personatus, and Callithrix geoffroyi live in the study area. Although variable, primate numbers were higher in larger than in smaller fragments, the likely reasons being the lack of space and food resources (fruits) and higher impact of mesopredators (small cats) in small fragments. The estimated densities are within the range reported for other Atlantic forest sites, except for brown howlers (Alouatta fusca), which were extremely rare. Estimates of population sizes were on the order of several hundreds to thousands of individuals/species in the large-sized fragments (ca. 20,000 ha), while comparable estimates for the other areas indicate <500 individuals/species in the medium-sized reserves (ca. 2,000 ha), and <50 individuals/species in the small fragments (ca. 200 ha). These estimates suggest that only Atlantic forest fragments 20,000 ha can harbor primate populations large enough to escape extinction in the long term. Given that <20% of all protected areas remaining in the Atlantic forest are 20,000 ha, management measures are urgently needed to improve primate conservation in this biome.     

Ectoenzymatic ratios in relation to particulate organic matter distribution (Ross Sea,Antarctica)

The results of a study on ectoenzymatic activity (the enzyme activity bound to particles larger than 0.2 micro m) and its relation to organic particle concentration are reported here. The sampling was carried out during the 1994 Antarctic spring, at a fixed station (Station 11) in the polynya of the Ross Sea, an area characterized by quick changes in sea ice cover. The sampling was repeated 4 times over a 20-day time period. The particulate organic matter distribution followed the physical structure of the water column, which depends on ice dynamics and is mainly determined by salinity. In the mixed-water surface layer (0-50 m) the concentrations were higher (on average 65.6 micro gC/L) than in the deeper water layer (50 m-bottom) (on average 19.1 micro gC/L). This distribution and quality, expressed by the protein:carbohydrate ratio, linked the particulate organic matter to the phytoplanktonic bloom which was in progress in the area. We determined the kinetic parameters of the glycolytic and proteolytic ectoenzymes and also the total activity for the proteolytic enzyme, in order to evaluate the contribution of the particle-bound activity. We observed higher values in the surface layer than in the deeper layer. b-Glucosidase activity ranged between 0.03 and 0.92 nmol L(-1) h(-1); b-N-acetylglucosaminidase activity was in the range of 0.04-0.58 nmol (L-1) (h-1). The total proteolytic activity (leucine aminopeptidase) ranged between 0.85 and 33.71 nmol L(-1) (h-1). The ectoproteolytic activity was about 35-60% of the total. The Km values were slightly higher for the proteolytic activity (on average 0.43 micro M for ectoproteolytic activity and 0.58 micro M for total proteolytic activity) than for the b-glucosidase (on average 0.36 micro M) and b-N-acetylglucosaminidase (on average 0.17 micro M), showing no remarkable variations in the water column. The ectoenzymatic ratios and their relationship with particulate organic substrates confirm the close link between organic substrate availability and degradation system response. The significant and positive correlations are not specific and suggest a prompt and efficient systemic response to the input of trophic resources. Nevertheless, changes in ectoenzyme activity and synthesis may act as adaptive responses to changing features of the ecosystem. In particular, variations in the proteolysis:glycolysis ratio depend on the functional features of the ecological system. In our study area this ratio is higher (about 10 or more) during production (particularly autotrophic) and lower (about 5 or less) during degradation/consumption events. The analysis of previous data, collected over a larger area characterized by different environmental conditions due to the changes of the pack ice cover, during the same cruise, confirms the existence of a significant relationship. Furthermore, the analysis of enzyme-uptake systems, expressed as Vmax:Km ratio, suggests that glycolytic ectoenzymes, although poorly expressed, may encourage microconsumers to grow rapidly on a wide range of organic substrates, including the refractory ones such as cellulose and chitin. However, low ectoenzyme potential exploitation rates of available organic substrates (on average about 5% for glycolytic and 12% for proteolytic ectoenzymes) would suggest that, during spring, zooplankton grazing or vertical and lateral transport are likely to play an important role in the removal of organic materials from the system.