Distribution, reactivity and vertical fluxes of methane in the Guadalquivir Estuary (SW Spain)

The influence of temperature, salinity, sediment-water-atmosphere exchanges and oxidation rate on the variability of methane (CH4) in the Guadalquivir Estuary has been studied. The database corresponds to 3 intensive samplings carried out in summer (2021 and 2022) and winter (2022). An increase in CH4 concentration towards the interior of the estuary has been observed, more intense during summer (19-371 nmol L-1). The influence of temperature and salinity on the variability of CH4 concentration is negligible, with contributions below 1 nmol L-1. Water-atmosphere fluxes increase inland in summer (28-574 μmol m-2 d-1), being generally higher than in winter (18-80 μmol m-2 d-1). Similarly, benthic fluxes remain relatively constant in winter (10 ± 6 μmol m-2 d-1) and increase inland in summer (7-212 μmol m-2 d-1). In the innermost station of the estuary, with salinities lower than 1, there is a significant increase in benthic fluxes, with values above 9000 μmol m-2 d-1. CH4 oxidation rates increase towards low salinities, being especially high in summer (489 nmol L-1 d-1). Based on the information obtained, CH4 variability in the Guadalquivir Estuary is mainly controlled by water-atmosphere fluxes, benthic fluxes and oxidation in the water column. The uncertainty associated with the quantification of these processes does not allow an adequate assessment of the influence of lateral inputs, although there is experimental evidence of their importance in the Guadalquivir.

Dynamics of CO2, CH4, and N2O in Ria Formosa coastal lagoon (southwestern Iberia) and export to the Gulf of Cadiz

A first characterization of greenhouse gases had been carried out to study their role and impact in a productive transitional coastal system of the southern Portugal - Ria Formosa lagoon. To this purpose, the partial pressure of CO2 (pCO2) and the concentration of dissolved CH4 and N2O have been measured. Two surveys were carried out during 2020, at low tide under typical conditions of Spring (March) and end of Summer (October). The samplings sites were distributed along the costal lagoon covering: i) inner areas with strong human impact (influence of different flows of treated wastewater discharges); and ii) main channels in connection with the main inlets to study the exchanges with the ocean. In general, the highest values of the three greenhouse gases were found at the inner studied areas, especially affected by the disposal of treated effluents from wastewater treatment plans, in October. The mean water - atmosphere fluxes of the CO2, CH4 and N2O are positive, showing that the study area acts as a source of these gases to the atmosphere. On the other hand, it was calculated a rough estimation of the three gases globally exported from Ria Formosa to the ocean, through the main six inlets to evaluate the magnitude of the supply of these gases from Ria Formosa to the adjacent ocean. The mean CO2, CH4 and N2O horizontal water fluxes exported from all the inlets of Ria Formosa to the Gulf of Cadiz for both seasons, during low water, are 8.7 ± 3.9 mmol m-2 s-1, 8.0 ± 3.5 μmol m-2 s-1 and 3.2 ± 1.5 μmol m-2 s-1, which corresponds to a mass transport through the inlets section of 0.7 ± 0.7 kg s-1, 0.2 ± 0.2 g s-1 and 0.2 ± 0.3 g s-1 respectively. From these estimates, as expected, the higher mass transport was found at the larger and deeper inlets (Faro-Olhão and Armona).

Greenhouse gas assemblages (CO2, CH4 and N2O) in the continental shelf of the Gulf of Cadiz (SW Iberian Peninsula)

This study examines the simultaneous water-atmosphere exchange of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) on the continental shelf of the Gulf of Cadiz, as well as the effect it has in terms of the radiative balance in the atmosphere, between 2014 and 2016. The experimental database consists of new measurements of the spatial and seasonal distribution of CO2 partial pressure (pCO2) and N2O concentration in 2016. pCO2 shows a wide range of variation influenced mainly by seasonal thermal variations (8.0 μatm 0C-1), as well as with the relative intensity of biological activity. There is experimental evidence of a progressive increase of pCO2 over the last 2 decades, with an estimated gradient of 4.2 ± 0.7 μatm y-1. During 2016, the Gulf of Cadiz acted as a slight source of CO2 to the atmosphere, with a mean flux of 0.4 ± 2.2 mmol m-2 d-1. The analysis of concentration variations in the water column shows that nitrification is the main N2O production process in the study area, although in the more coastal zone there are signs of inputs related to continental and sediment contributions, most probably induced by denitrification processes. In 2016, the Gulf of Cadiz acted as a weak sink of atmospheric N2O, with a mean flux of -0.1 ± 0.9 μmol m-2 d-1. From previous studies, performed with a similar methodology, an interannual database (2014-2016) of water-atmosphere fluxes of CO2, CH4 and N2O, normalized to the mean wind speed in the area, has been generated. Considering their respective Global Warming Potential (GWP) a joint greenhouse gasses (GHG) flux, expressed in CO2 equivalents of 0.6 ± 2.0 mmol m-2 d-1, has been estimated, which extended to the area of study indicates an approximate emission of 67.9 Gg CO2 y-1. However, although there is a high uncertainty associated with the spatial, temporal and interannual variations of CO2, CH4 and N2O fluxes in the Gulf of Cadiz, the exchange of greenhouse gasses could be influencing a radiative forcing increase in the atmosphere. When considering the available information on local and global estimates, the uncertainty about the effect of the joint exchange of GHGs to the atmosphere from the coastal seas increases significantly.

Dissolved organic matter distribution in the water column and sediment pore water in a highly anthropized coastal lagoon (Mar Menor, Spain): Characteristics, sources, and benthic fluxes

Coastal lagoons are among the most productive and biodiverse systems in the world and are important sentinels of climate change. The Mar Menor is one of the largest coastal lagoons in the Mediterranean, providing a variety of ecosystem services and resources to the community. However, in recent decades this lagoon has suffered drastic changes and degradation caused by human activities. We analyzed the concentration of dissolved organic carbon (DOC) and the optical properties of dissolved organic matter (DOM) in the water column and sediment pore water during the summer and winter of 2018 and during eighteen months from 2016 to 2018. Overall, we found that the composition of DOM is mainly related to and enhanced by anthropogenic activities and microbial metabolism. DOM enters the lagoon via urban and agricultural runoff, drainage systems, and wastewater treatment plants. Additionally, strong microbial metabolism in sediments leads to differences in DOM composition between water and sediments. In the water column, humic-like components accounted for 71 % of the total DOM, while protein-like compounds were most abundant in sediment pore water. We observed a strong seasonal variability associated with precipitation and the system collapse in 2016 (phytoplankton bloom), which resulted in the death of 80 % of macrophytes. The sediments act as a source of DOM to the overlying water, likely due to relatively high organic matter content and intense microbial activity, primarily through anaerobic pathways. Benthic fluxes of DOC ranged from 5.24 to 33.30 mmol m-2 d-1, being higher in winter than summer 2018 and decreasing from north to south, likely related to lower residence time in the northern basin, groundwater discharge and accumulation of organic matter from the dead meadows. We estimate a net flux of DOC from the Mar Menor toward the Mediterranean Sea of 1.57 × 107 mol yr-1.

First trans-eunicellane terpene synthase in bacteria

Terpenoids are the largest family of natural products, but prokaryotes are vastly underrepresented in this chemical space. However, genomics supports vast untapped biosynthetic potential for terpenoids in bacteria. We discovered the first trans-eunicellane terpene synthase (TS), AlbS from Streptomyces albireticuli NRRL B-1670, in nature. Mutagenesis, deuterium labeling studies, and quantum chemical calculations provided extensive support for its cyclization mechanism. In addition, parallel stereospecific labeling studies with Bnd4, a cis-eunicellane TS, revealed a key mechanistic distinction between these two enzymes. AlbS highlights bacteria as a valuable source of novel terpenoids, expands our understanding of the eunicellane family of natural products and the enzymes that biosynthesize them, and provides a model system to address fundamental questions about the chemistry of 6,10-bicyclic ring systems.

Phytotherapeutic alternatives for neurodegenerative dementias: Scientific review, discussion and therapeutic proposal

The incidence and prevalence of age-related neurodegenerative dementias have been increasing. There is no curative therapy and conventional drug treatment can cause problems for patients. Medicinal plants traditionally used for problems associated with ageing are emerging as a therapeutic resource. The main aim is to give a proposal for use and future research based on scientific knowledge and tradition. A literature search was conducted in several searchable databases. The keywords used were related to neurodegenerative dementias, ageing and medicinal plants. Boolean operators and filters were used to focus the search. As a result, there is current clinical and preclinical scientific information on 49 species used in traditional medicine for ageing-related problems, including neurodegenerative dementias. There are preclinical and clinical scientific evidences on their properties against protein aggregates in the central nervous system and their effects on neuroinflammation, apoptosis dysregulation, mitochondrial dysfunction, gabaergic, glutamatergic and dopaminergic systems alterations, monoamine oxidase alterations, serotonin depletion and oestrogenic protection. In conclusion, the potential therapeutic effect of the different medicinal plants depends on the type of neurodegenerative dementia and its stage of development, but more clinical and preclinical research is needed to find better, safer and more effective treatments.

Investigation of Acid–Base Catalysis in Halimadienyl Diphosphate Synthase Involved in Mycobacterium tuberculosis Virulence

The devastating human pathogenMycobacterium tuberculosis (Mtb) is able to parasitize phagosomal compartments within alveolar macrophage cells due, in part, to the activity of its cell-surface lipids. Prominent among these is 1-tuberculosinyl-adenosine (1-TbAd), a derivative of the diterpenoid tuberculosinyl (halima-5,13-dienyl) diphosphate produced by the class II diterpene cyclase encoded by Rv3377c, termed here MtHPS. Given the demonstrated ability of 1-TbAd to act as a virulence factor for Mtb and the necessity for Rv3377c for its production, there is significant interest in MtHPS activity. Class II diterpene cyclases catalyze a general acid–base-mediated carbocation cascade reaction initiated by protonation of the terminal alkene in the general diterpenoid precursor (E,E,E)-geranylgeranyl diphosphate and terminated by deprotonation of the final cyclized (and sometimes also rearranged) intermediate. Here, structure-guided mutagenesis was applied to characterize the various residues contributing to activation of the enzymatic acid, as well as identify the enzymatic base in MtHPS. Particularly given the ability of conservative substitution for the enzymatic base (Y479F) to generate an alternative product (labda-7,13-dienyl diphosphate) via deprotonation of an earlier unrearranged intermediate, further mutational analysis was carried out to introduce potential alternative catalytic bases. The results were combined with mechanistic molecular modeling to elucidate how these mutations affect the catalytic activity of this important enzyme. This not only provided detailed structure–function insight into MtHPS but also further emphasized the inert nature of the active site of MtHPS and class II diterpene cyclases more generally.

Dynamic of CO2, CH4 and N2O in the Guadalquivir estuary

The concentration of dissolved CH₄ and N₂O, as well as the partial pressure of CO₂ (pCO₂) were studied in the Guadalquivir estuary. Samples were taken in March and April 2018 and 2019, under different rainy and tidal conditions. The available database for summer 2017 (Sierra et al., 2020) was included in the interpretation of the factors that determine the variability of these gases in the Guadalquivir estuary. Two different types of samplings were carried out: a longitudinal transect across the river with salinity values close to zero and another one during two consecutive tidal cycles in the mouth of the estuary. The highest concentrations were found in the upper zone of the estuary and during the low tide. This distribution was related to 4 factors: temperature, salinity, exchange with the atmosphere, and biochemical processes together with the river inputs. Temperature is one of the factors that clearly seems to determine the distribution of gases and fluxes, showing the highest values in the upper zone during the summer of 2017. Intense rains cause a dilution effect of the gas in the water column, this provoked, during the season of spring 2018, an increase in the salinity factor in the distribution of gases in the middle zone. High concentrations of the gases have been linked to production processes in the water column, as well as to benthic production and lateral inputs. While the gases concentrations at the mouth presented values close to those of the equilibrium with the atmosphere, the fluxes in the upper zone of the estuary reached average values of 89.6 mmol m^-2 d^-1, 121.7 μmol m^-2 d^-1 and 59.9 μmol m^-2 d^-1 for CO₂, CH₄ and N₂O, respectively. Generally, water-atmosphere fluxes are positive through the whole study, which means that the estuary acts as a source of these gasses to the atmosphere.

Validation of leadless atrioventricular synchronous pacing with Holter-ECG: a pilot study

Background

The novel MICRA AV leadless pacemaker can provide atrioventricular (AV) synchronous pacing using an accelerometer-based atrial sensing algorithm.

Purpose

To describe the performance of MICRA AV pacemaker in a real-life setting and to determine the agreement between AV synchrony determined by the device counters and AV synchrony obtained by a 24 h ECG Holter test.

Methods

This pilot study included the first ten patients implanted with a MICRA AV leadless pacemaker at our institution. All implants were performed according to standard protocols and under deep sedation. A close follow-up was performed, and atrial sensing parameters were adjusted following AV synchrony given by the device counters. Patients underwent a 24 h ECG Holter test once AV synchrony remained stable for at least two months. The ECG Holter signal was analyzed in a blinded manner by an automatic delineation system based on the wavelet transform (Figure). This algorithm has a sensivity of 98.9% and a positive predictive value of 91.9% to detect p waves. Cardiac cycles were defined as synchronous if a QRS complex followed the P-wave by ≤300 ms, according to MARVEL 2 study criterion. AV synchrony obtained from the 24 h Holter test was compared with AV synchrony extracted from the device counters (AM-VP + AM-VS) during the same 24 h.

Results

From June to November 2020, 10 patients (7 males, mean age 83.5±5.4) were implanted with a MICRA AV leadless pacemaker (5 patients due to complete AV block and 5 patients due to second degree AV block). All devices were implanted after 1 deployment and no major complications appeared. Data related to implant parameters are displayed in Table 1. Device reprogramming was needed in all patients during follow-up. The 24 h ECG Holter monitoring was performed 141.4±45 days after the implant (mean time). Device settings and programming at Holter date is displayed in Table 1. Total ECG recorded time was 210.6 h and 915,488 cardiac cycles were analyzed. The mean percentage of synchronous cardiac cycles was 88.6±8.5% of total cycles while the mean AV synchrony determined by the device counters (AM-VP + AM-VS) during those 24 h was 89.8±5.5%. A good patient to patient correlation between these two measures was found (coefficient of intraclass correlation = 0.72).

Conclusions

We obtained high rates of AV synchrony with MICRA AV leadless pacemaker, in our short-term follow-up pilot study. Manual adjustment of the atrial sensing parameters, guided by the device counters, seems to be useful to obtain an optimal performance.

Funding Acknowledgement

Type of funding sources: None.

Linkages between greenhouse gases (CO2, CH4, and N2O) and dissolved organic matter composition in a shallow estuary

Estuarine systems receive large amounts of organic matter that enhance the production of greenhouse gases (GHGs), such as carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O). Despite considerable research on GHGs and dissolved organic matter (DOM) distribution in estuaries, little is known about the linkage between these gases and DOM composition. Here we evaluated the relationship between three GHGs (CO₂, CH₄, and N₂O) and DOM composition, determined through optical properties, in Guadalete estuary (Bay of Cadiz, Spain). The partial pressure of CO₂, and CH₄ and N₂O concentrations ranged between 332.8 and 6807.1 μatm, 19.9-6440.1 nM, and 6.8-283.9 nM, respectively. Thus, the Guadalete estuary was a source of CO₂, CH₄ and N₂O to the atmosphere. We validated three PARAFAC components related to humic-like fluorescence from terrestrial, microbial and effluent sources, and one with protein-like material. Humic-like components accounted for 86% ± 6% of the total FDOM pool, indicating a predominantly allochthonous DOM origin. The three GHGs were significantly linked to DOC concentration and DOM composition, exhibiting different patterns in these linkages. Terrestrial and microbial humic-like substances with increasing aromaticity might enhance pCO₂ in Guadalete estuary. Dissolved CH₄ concentrations showed the strongest relationship with DOM composition, indicating that humic and protein-like material are linked with their distribution. In contrast, dissolved N₂O was only related with the protein-like fraction and with humic-like material derived from anthropogenic activities (sewage and agriculture). Our results further indicate that a possible coupling between benthic fluxes of GHGs and DOM might be occurring in this shallow estuary. We conclude that it is important to account for DOM composition when studying GHGs distribution in estuarine systems to understand their roles and potential responses associated with climate change.

"Greenhouse gas dynamics in a coastal lagoon during the recovery of the macrophyte meadow (Mar Menor, SE Spain)"

The Mar Menor is a hypersaline coastal lagoon with salinity values ranging from 41.9 to 45.5. The system is subjected to a high anthropic pressure that causes an intense eutrophication process, followed by a recovery of the macrophyte meadows. This study focuses on the distribution of the main greenhouse gases (CO₂, CH₄ and N₂O) and was carried out in the extreme seasonal conditions of winter and summer during the year 2018. Sediment-water-atmosphere exchanges and biochemical processes in the water column appeared to be the main factors to explain the variability of these gases. Dissolved Inorganic Carbon (DIC), CH₄ and N₂O benthic fluxes values obtained in this study, were of 91 ± 29 mmol m^-2 d^-1, 3.9 ± 1.9 μmol m^-2 d^-1 and -0.65 μmol m^-2 d^-1, respectively, along with an important seasonal variation observed, with an increase of DIC and CH₄ benthic fluxes during the summer season. Mean values of partial pressure of CO₂ (pCO₂) in surface water were of 579 μatm in winter and 464 μatm in summer, therefore we can establish that the Mar Menor acts as a source of this gas emitting 3.3 ± 3.0 mmol CO₂ m^-2 d^-1 to the atmosphere. In spite of this, the Mar Menor has a strong autotrophic behaviour partly due to the recovery of the macrophyte meadows, presenting an estimated NEP of 101 mmol m^-2 d^-1. Regarding to CH₄, the mean fluxes to the atmosphere were of 8.0 ± 5.8 μmol m^-2 d^-1 and there was evidence of CH₄ production in the water column that increased in summer. Last of all, in the case of N₂O the system acts as a sink with values of -0.65 ± 0.5 μmol m^-2 d^-1, presenting an intake of N₂O that is usually detected in pristine systems.

Medicinal plants and natural products as neuroprotective agents in age-related macular degeneration

The retina may suffer neurodegenerative damages, as other tissues of the central nervous system do, and serious eye diseases may develop. One of them is age-related macular degeneration, which causes progressive loss of vision due to retina degeneration. Treatment of age-related macular degeneration focuses on antioxidant agents and anti-vascular endothelial growth factor compounds, among others, that prevent/diminish oxidative stress and reduce neovascularisation respectively. The phytochemicals, medicinal plants and/or plant-diet supplements might be a useful adjunct in prevention or treatment of age-related macular degeneration owing to their antioxidant and anti-vascular endothelial growth factor properties. This review article presents the most investigated plants and natural products in relation to age-related macular degeneration, such as saffron, ginkgo, bilberry and blueberry, curcuma or turmeric, carotenoids, polyphenols, and vitamins C and E. This study provides up-to-date information on the effects, treatments, safety and efficiency of these phytotherapy products.

Singlet oxygenation of triquinacene, barrelene, and homobarrelene

The singlet oxygenation of three polycyclic hydrocarbons, triquinacene, barrelene and homobarrelene was studied. Triquinacene reacted by way of a perepoxide intermediate, transferring an oxygen atom to another triquinacene molecule to give exclusively the mono epoxide. Barrelene, on the other hand, underwent a rare homo-Diels-Alder reaction with 1O2 to give the decomposition product from the initial tetracyclic 1,2-dioxolane leading to benzofuran. The latter reacted with 1O2 in a [2+2] cycloaddition to give an unstable 1,2-dioxetane which collapsed to 2-formylphenyl formate. The latter was independently synthesize via singlet oxygenation of authentic benzofuran. Homobarrelene reacted in a similar fashion to give a homoDiels product, decomposition of which led to a keto aldehyde which was characterized spectroscopically. Computational work confirms the barrelene and homobarrelene reactions with 1O2 as concerted [π2s+π2s+π2s] cycloadditions.

Neuroprotective Potential of Ginkgo biloba in Retinal Diseases

Like other tissues of the central nervous system, the retina is susceptible to damage by oxidative processes that result in several neurodegenerative disease such as age-related macular degeneration, diabetic retinopathy, glaucoma, ischaemic retinal disease, retinal disease produced by light oxidation, and detached retina, among other diseases. The use of antioxidant substances is a solution to some health problems caused by oxidative stress, because they regulate redox homeostasis and reduce oxidative stress. This is important for neurodegeneration linked to oxidation processes. In line with this, Ginkgo biloba is a medicinal plant with excellent antioxidant properties whose effects have been demonstrated in several degenerative processes, including retinal diseases associated with neurodegeneration. This review describes the current literature on the role of ginkgo in retinal diseases associated with neurodegeneration. The information leads to the conclusion that G. biloba extracts might be a good option to improve certain neurodegenerative retinal diseases, but more research is needed to determine the safety and efficacy of G. biloba in these retinal degenerative processes.

Distribution of N2O in the eastern shelf of the Gulf of Cadiz (SW Iberian Peninsula)

Distribution of N₂O has been determined in eight cruises along three transects (Guadalquivir, Sancti Petri and Trafalgar) in the Gulf of Cadiz, during 2014 and 2015. The mean N₂O value for this area was 10.0±0.9nM, with large spatial and temporal variations. Stratification in the water column has been observed; the concentration of this gas increases with the depth, because of the presence of the Eastern North Atlantic Central Water (ENACW) and the Mediterranean Outflow Waters (MOW). The N₂O production measured in this study is mainly due to nitrification. N₂O yields from nitrification were estimated from the linear correlation of the excess of N₂O (ΔN₂O) with Apparent Oxygen Utilization (AOU) and nitrate (NO₃^-), with values of their slopes ranged between 0.010 and 0.021% and 0.017-0.025% respectively. There is an onshore - offshore gradient of N₂O; the highest values were found at the shallower stations, indicating coastal input and benthic remineralization. The seawater-air flux of N₂O is affected by several variables (temperature, AOU and NO₃^-), and the average flux calculated is 2.7±2.0μmolm^-2d^-1. The fluxes show a decrease with increasing distance from the coast, and with proximity to the Strait of Gibraltar. The study area behaves as a source of N₂O to the atmosphere, with a global emission of 0.18Ggyear^-1.

Spatial and seasonal variability of CH4 in the eastern Gulf of Cadiz (SW Iberian Peninsula)

Methane (CH₄) concentrations were measured along three sections of the eastern Gulf of Cadiz (designated "Guadalquivir", "Sancti Petri" and "Trafalgar") during eight cruises in 2014 and 2015. The concentration of CH₄ varied from 3.6 to 19.7nmolkg^-1 (CH₄ saturation percent of 122 and 916%), showing seasonal variation. The highest values were found in December 2014 and November 2015. In most of the sampling area the highest concentration of CH₄ was found in subsurface waters at depths close to the thermocline, and in the bottom waters near the coast. The seawater-air flux of CH₄ ranged between 0.8 and 59.7μmolm^-2d^-1, showing seasonal variation in function of the temperature of the surface water. In the "Guadalquivir" and "Sancti Petri" sections, the CH₄ fluxes increased with proximity to the coast; this may be a result of continental inputs and CH₄ emissions from sediments. The whole study area behaves as a source of CH₄ to the atmosphere with mean values of 0.5 and 0.6GgCH₄yr^-1 in 2014 and 2015, respectively.

Anthropogenic effects on greenhouse gas (CH4 and N2O) emissions in the Guadalete River Estuary (SW Spain)

Coastal areas are subject to a great anthropogenic pressure because more than half of the world's population lives in its vicinity causing organic matter inputs, which intensifies greenhouse gas emissions into the atmosphere. Dissolved concentrations of CH4 and N2O have been measured seasonally during 2013 in the Guadalete River Estuary, which flows into the Cadiz Bay (southwestern Spanish coast). It has been intensely contaminated since 1970. Currently it receives wastewater effluents from cities and direct discharges from nearby agriculture crop. Eight sampling stations have been established along 18 km of the estuary. CH4 and N2O were measured using a gas chromatograph connected to an equilibration system. Additional parameters such as organic matter, dissolved oxygen, nutrients and chlorophyll were determinate as well, in order to understand the relationship between physicochemical and biological processes. Gas concentrations increased from the River mouth toward the inner part, closer to the wastewater treatment plant discharge. Values varied widely within 21.8 and 3483.4 nM for CH4 and between 9.7 and 147.6 nM for N2O. Greenhouse gas seasonal variations were large influenced by the precipitation regime, masking the temperature influence. The Guadatete Estuary acted as a greenhouse gas source along the year, with mean fluxes of 495.7 μmol m(-2)d(-1) and 92.8 μmol m(-2)d(-1) for CH4 and N2O, respectively.

Health-related Quality of Life before and after a solid organ transplantation (kidney, liver, and lung) of four Catalonia hospitals

INTRODUCTION AND AIMS

It has been described that patients who receive a transplant display a better Health Related Quality of Life (HRQoL). Our objective was to describe the HRQoL before and after a solid organ transplantation, comparing results among various transplantations.

METHODS

This HRQoL study using the SF-36 was implemented before as well as at 3 and 12 months posttransplantation. Posttransplantation were compared with pretransplantation scores as well as with the general population.

RESULTS

One hundred sixty-two renal, 159 liver, and 58 lung candidates were included before transplantation, among whom there were 126 renal, 108 liver, and 22 lung recipients. The median age of all transplant recipients was 53 years with 68% men. The various transplant types began with different HRQoL: lung showed the worst, followed by the liver, and then renal. The scores of the SF-36 before and 3 months posttransplantation showed significant improvements, except for "Pair." At 12 versus 3 months, mental health was somewhat better for renal, and almost all dimensions showed significant improvement for liver and lung patients. All subjects showed clear improvements after transplantation.

CONCLUSION

All patients showed clear improvements after transplantation when mental health was compared with the general population, particularly lung transplant recipients who expressed the greatest improvement. However, they still showed deficits in physical health.

Perceived state of health is worse in kidney recipients younger than 60 years vs older than 60 years

OBJECTIVE

To evaluate the differences in perceived state of health (PSH) according to patient age younger or older than 60 years.

PATIENTS AND METHODS

One hundred sixty-two patients were entered on the waiting list for renal transplantation from July 2003 at 4 hospitals in California and were observed prospectively for 2 years. Data were obtained at baseline and at 3 and 12 months after transplantation. All patients answered a generic Perceived State of Health (PSH) questionnaire, the 36-item Short-Form Health Survey (SF-36), and the EuroQol (EQ-5D) questionnaire. Data were analyzed using the t test for independent variables and the chi(2) test for contingency tables.

RESULTS

Patients aged 60 years or older had higher PSH scores compared with those younger than 60 years on all dimensions of the SF-36 and on the 2 summary scores. Scores for the physical domains were significantly improved at all follow-up visits. After transplantation, scores for the EQ-5D were higher for older patients vs younger patients (mean [SD], 80 [16] vs 67 [14]; P = .01). The PSH score for the older patients was similar to that for the general population (>45 points). The PSH scores for the physical and mental health domains were worse for the younger patients compared with the general population; no differences were noted for clinical variables.

CONCLUSION

Patients older than 60 years have higher PSH scores compared with patients younger than 60 years. However, scores for the younger patients were significantly improved at 1 year after transplantation.

Impact of health related quality of life in Catalonia liver transplant patients

OBJECTIVE

Our aim was to study the changes in the Health Related Quality of Life (HRQoL) during the first year following liver transplantation.

MATERIALS AND METHODS

Among 159 patients awaiting orthotopic liver transplantation (OLT) who were prospectively studied at 4 hospitals in Catalonia, 108 actually obtained an organ. HRQoL over time, namely, before, as well as at 3 and 12 months after transplantation, was recorded using the Short Form-36 (SF-36) and the Liver Disease Quality of Life (LDQOL 1.0). After we searched medical, clinical, and sociodemographic records to examine the studied variables on the HRQoL at each moment, the significance was explored using t tests and one-way analysis of variance (ANOVA).

RESULTS

Comparison of the SF-36 dimensions before and at 3 months after transplantation revealed almost all domains to show significant improvements (P < .01), except bodily pain, role-physical, social functioning, and PCS. Comparisons between 3 and 12 months after transplantation showed only significant improvements in role-physical, physical functioning, and PCS (P < .05). The other dimensions showed similar or slightly better scores, but the differences were not significant. For LDQOL 1.0 before and 3 months after transplantation, the dimensions with significant differences (P < .01) were: effects of liver disease on activities of daily living; concentration; health distress; sleep problems; stigmata of liver disease; and sexual function. Comparing 3 and 12 months posttransplantation, no dimension showed a significant improvement. A negative correlation existed between hypertensive patients and PCS on the SF-36 (P < .001). The clinical diagnosis of alcoholic liver disease showed better scores in some dimensions of the LDQOL than the other diagnoses. Female subjects showed significantly worse HRQoL than men (P < .001). Child-Pugh and Model for End-Stage Liver Disease (MELD) classifications were not associated with the HRQoL either before or after transplantation.

CONCLUSIONS

The most important finding in this study was that all domains showed significant improvements in HRQoL at 3 months after transplantation with only slight improvements at 12 months.

Study of red wine neuroprotection on astrocytes

Phenolic composition of wine depends not only on the grape variety from which it is made, but on some external factors such as winemaking technology. Red wine possesses the most antioxidant effect because of its high polyphenolic content. The aim of this work is to study for the first time, the neuroprotective activity of four monovarietal Spanish red wines (Merlot (ME), Tempranillo (T), Garnacha (G) and Cabernet-Sauvignon (CS)) through its antioxidant ability, and to relate this neuroprotection to its polyphenolic composition, if possible. The wine effect on neuroprotection was studied through its effect as free radical scavenger against FeSO4, H2O2 and FeSO4 + H2O2. Effect on cell survival was determined by 3(4,5-dimethyltiazol-2-il)-2,5-diphenyltetrazolium reduction assay (MTT) and lactate dehydrogenase (LDH) release assay on astrocytes cultures. Results showed that most of the studied wine varieties induced neuroprotection through their antioxidant ability in astrocytes, Merlot being the most active; this variety is especially rich in phenolic compounds, mainly catechins and oligomeric proanthocyanidins. Our results show that red wine exerts a protection against oxidative stress generated by different toxic agents and that the observed neuroprotective activity is related to their polyphenolic content.

Efficacy of peritoneal ultrafiltration in the treatment of refractory congestive heart failure

BACKGROUND

Heart failure (HF) is a major health problem in developed countries. HF is a progressive, lethal disorder, even with adequate treatment. There exists a vicious circle in the pathophysiology of HF that perpetuates and magnifies the problem. Concomitant fluid accumulation may worsen the congestive HF, it is responsible for numerous hospitalizations and it is an important cause of mortality. In this situation, any means of fluid removal may aid in the management of these patients. The objective of this study was to evaluate the efficacy of peritoneal dialysis (PD) in the treatment of refractory HF in terms of functional status, hospitalization and mortality. We also determined the improvement in health-related quality of life with the use of PD, and examined the economic consequences of its use.

METHODS

We conducted a single centre, prospective, non-randomized study involving patients showing symptoms and signs of congestive HF refractory to maximum tolerable drug treatment. All of them were treated with PD. We analysed physical and biochemical determinations, functional status (according to the NYHA classification) and echocardiogram parameters. Also, to determine the efficacy of the technique we compared the perceived state of health (measured by the EQ5D) to PD patients respect to those reported with conservative therapies. Finally, we carried out a cost-utility evaluation measured by the incremental cost-utility ratio between these two options.

RESULTS

Seventeen patients (65% men, 64 +/- 9 years) were included in the study, and 12 were still undergoing PD treatment at the end of the follow-up period (15 +/- 9 months). All patients improved their NYHA functional status (65% two classes; the rest, one; P < 0.001), with an important improvement in their pulmonary artery systolic pressure (44 +/- 12 versus 27 +/- 9 mmHg; P = 0.007), but no changes in left ventricular ejection fraction. Hospitalization rates underwent a dramatic reduction (from 62 +/- 16 to 11 +/- 5 days/patient/year; P = 0.003) before and after PD treatment. PD treatment raised life expectancy of 82% after 12 months of treatment, and 70% and 56% after 18 and 24 months, respectively, much better outcomes than those reported about conservative therapies, which only use diverse diuretic regimens. PD was associated with a higher perception state of health than the conservative therapy (0.6727 versus 0.4305; P < 0.01). Finally, we found that PD is cost-effective compared with the conservative therapy.

CONCLUSIONS

We demonstrate that congestive HF programmes should consider offering PD in hope of seeing better functional status, reduced morbidity and mortality, better quality of life as well as reduced health care costs.

Erythropoietin Safety and Efficacy in Chronic Allograft Nephropathy

BACKGROUND

Patients with chronic allograft nephropathy (CAN) very frequently suffer anemia. Correction of anemia by means of recombinant erythropoietin (rEpo) is possible and useful, but safety and efficacy must be assessed.

METHODS

This multicenter, prospective, open study included patients with a cadaver renal transplant, CAN, and non-ferropenic anemia. The aim of the study was to determine the safety and efficacy of treatment with rEpo to target hematocrit (HCT) values around 35% and/or hemoglobin (Hb) levels of 11 g/dL.

RESULTS

Twenty-four patients were included: 71% males and 29% females aged 49.5 +/- 14 years. At last follow-up, 48% did not show anemia-related symptoms, and 19% experienced adverse events possibly or probably related to rEpo. In 86% of cases, anemia was corrected and in 71%, graft survival was conserved. Patients whose anemia was not corrected had poor initial renal function (sCr 5 +/- 1 mg/dL vs sCr 3.2 +/- 1 mg/dL, P = .028). Patients with graft survival showed correction of anemia (P = .001) on a relatively low dose of rEpo and without a significant increase in blood pressure.

CONCLUSIONS

All patients who had graft survival and only half of those who lost their graft showed a correction of anemia. The rEpo treatment neither accelerated nor decelerated renal failure. The difference between patients in whom anemia was corrected, or not, did not depend upon the previous level of HCT/Hb, but upon worse renal function. Thus, rEpo in patients with CAN is safe and effective, so administration should be initiated early to avoid adverse events deriving from anemia.

Vaccination with a neural-derived peptide plus administration of glutathione improves the performance of paraplegic rats

After damage to the central nervous system (CNS) the body is protected by an adaptive immune response which is directed against myelin-associated proteins. Active immunization with nonpathogenic derivatives of CNS-associated peptides (DCAP) reduces the degeneration of neurons and promotes motor recovery after spinal cord injury (SCI) in rats. In order to improve even more the neurological outcome obtained with this therapy, either a combination of DCAP immunization plus glutathione monoethyl ester (GSHE) or a double DCAP immunization were performed. GSHE is a cell-permeant derivative of glutathione, a potent antioxidant agent that significantly inhibits lipid peroxidation after SCI. After a contusive or compressive SCI, the combination of GSHE + DCAP immunization, induced better motor recovery, a higher number of myelinated axons and better rubrospinal neuron survival than immunization alone. On the other hand, double-DCAP immunization counteracted the protective effect of DCAP therapy. Motor recovery and neuronal survival of double-immunized rats were similar to those observed in control animals (PBS-treated). Further studies revealed that double immunization was not encephalitogenic but inhibited the proliferative response of T-cells specific to the DCAP-immunized peptide. This clonal dysfunction was probably secondary to anergy. GSHE improves the protective effect induced by DCAP immunization while double immunization, reverts it.

Estimación de un índice de utilidad mediante el uso de la versión española del Cuestionario de Salud SF-36: validez del índice SF-6D frente al EQ-5D

BACKGROUND AND OBJECTIVE

A new utility index derived of the SF-36, the SF-6D, was recently developed and has been compared with other utility measures. The objective was to validate this index in the Spanish version of SF-36 with respect to the EQ-5D.

METHOD

1,843 complete measures of the SF-36 and the EQ-5D from 1,283 patients who received a solid organ transplant were collected. SF-6D values were calculated using the model proposed by its creator and without tariff values (not weighted). EQ-5D values were calculated using Spanish visual analog scale tariff (VAS-t), the time-trade off tariff (TTO-t) and also without tariff values (not weighted). Spearman correlation coefficients were calculated between SF-6D and EQ-5D values.

RESULTS

Mean value (standard deviation) of SF-6D was 0.67 (0.15), of VAS-t, 0.69 (0.24) and of TTO-t, 0.70 (0.32). SF-6D values had moderate correlation with VAS-t (r = 0.734) and TTO-t (r = 0.731) (both p < 0.001). The not weighted SF-6D had a high correlation with the weighted version (r = 0.969, p < 0.001), and moderate with the VAS-t (r = 0.754), TTO-t (r = 0.750) and no weighted EQ-5D (r = 0.784) (p < 0.001).

CONCLUSIONS

The SF-6D index derived from the Spanish version of SF-36 seem to be a valid utility index to be used with the SF-36 databases from studies made in Spain.

Differences in health-related quality of life between elderly and younger patients on hemodialysis

BACKGROUND

It has been demonstrated that elderly patients have a great capacity of adaptation to renal replacement therapy (RRT). The aim of this study was to assess the health-related quality of life (HRQoL) of a cohort of patients at 3 and 12 months after the start of hemodialysis, searching for differences between elderly (aged>or=65 years) and younger (aged <65 years) patients.

METHODS

This was a longitudinal prospective study of 93 patients starting RRT. HRQoL was assessed using the SF-36 health survey and the physical symptom dimension of the Kidney Disease Questionnaire (KDQ) at 3 and 12 months from the start of RRT. Physical component summary (PCS), mental component summary (MCS) and standardized scores, in which a lower score indicated lower HRQoL, by age and sex were obtained.

RESULTS

Mean (SD) age was 66 years (12.26 years). At 3 months, differences between younger patients and elderly ones were statistically significant in the general health dimension, and at 12 months in physical functioning, role physical, general health dimensions and PCS, indicating less loss of HRQoL in elderly patients. At 3 months it was found that the functional state measured on the Karnofsky scale was independently associated with PCS (p=0.003), and hematocrit to MCS (p=0.036). At 1 year, PCS was independently associated with age (p=0.043) and Karnofsky score (p=0.039).

CONCLUSIONS

Using scores standardized by age and sex, elderly patients had less loss of HRQoL in the physical aspects, than younger patients at 1 year from the start of hemodialysis.

Study on Health-Related Quality of Life in Patients With Advanced Heart Failure Before and After Transplantation

Our objective was to evaluate health-related quality of life in patients with advanced heart failure on the waiting list for a heart transplant.

MATERIALS AND METHODS

The study was performed using the EUROQOL-5D questionnaire (EQ-5D) on 38 patients (age: 53 +/- 2 years, 82% men) who were analyzed consecutively during the pretransplant period, as well as at 3, 6, and 12 months after transplantation. We excluded pediatric transplants, retransplantations, heart and lung transplantation, and patients scoring below 17 points on the Folstein's Cognitive Mini-Examination. The studied variables included the five dimensions of the EQ-5D test: mobility, self-care, daily activities, pain-discomfort, anxiety and depression; a visual analog scale from 0 to 100; and perception of health status. Statistics included analysis of variance and chi-square tests. Significance was set at P < .05.

RESULTS

There were significant differences in all tested parameters. The worst values were observed prior to transplantation, with a significant improvement at 3 months.

CONCLUSIONS

Patients with heart failure showed a significant impairment in health-related quality of life before transplantation. The improvement in health-related quality of life was significant and rapidly evident in the posttransplantation period. The most affected dimensions were activities of daily living and pain-discomfort. All dimensions became stable at 3 months, except for anxiety and depression. At 6 to 12 months, a plateau was reached in the feelings of well-being.

Mental health at the third month of haemodialysis as a predictor of short-term survival

BACKGROUND

The aim of this study was to evaluate the survival of patients initiating haemodialysis (HD), and to analyse whether low health-related quality of life (HRQoL) levels are predictors of mortality in the short-term, controlling certain variables that had been shown in other studies to have a bearing on survival, and using scores, standardized for age and sex, of the HRQoL measurement tool employed.

METHODS

This is a multicentric prospective study of all patients on HD in all the dialysis units in Asturias, a region with a little over one million inhabitants, from 1 January 2001 to 30 September 2002. A total of 199 patients initiated HD in our region and survived the first 3 months. Of these, 137 patients who remained on HD for at least 3 months had complete responses on HRQoL measures.

RESULTS

It was observed that adjusted relative risk (RR) of death increased by 5% for each year of age increase (RR=1.05, 95% CI 1.01-1.09: P=0.006); in the same way, for each increase in the Mental Component Summary (MCS) score, the adjusted RR of death diminished by 4% (RR=0.96, 95% CI 0.94-0.99; P=0.006).

CONCLUSION

Mental health has been shown to be a factor independently associated with mortality; as the MCS score worsens the adjusted RR of death of a patient on HD increases.

Posttransplantation Diabetes Mellitus: Prevalence and Risk Factors

BACKGROUND

Prevalence of diabetes mellitus (DM) type 2 in Asturias is 10%. The associations between age, family history of diabetes, hypertension, obesity, hypertriglyceridemia, and development of type 2 diabetes are well established. The aim of this study was to evaluate the prevalence of and risk factors for posttransplantation diabetes mellitus (PTDM).

METHODS

We retrospectively studied 500 patients who had received a cadaveric renal transplant. Subjects with pretransplantation diabetes (5.6% type 1 and 7% type 2) and nondiabetics (78.2%) were excluded. We only evaluated 46 (9.2%) patients with PTDM. The follow-up period was 6 months to 15 years. We reviewed gender, age, family history of diabetes, body weight, hypertension, cardiovascular events, serum creatinine, hepatitis C virus infection, triglycerides, hyperuricemia, high-density lipoprotein and low-density lipoprotein cholesterol, and immunosuppressive therapies.

RESULTS

The median time to diagnosis of PTDM was 3 months (range 1-56 months) after transplantation, a period in which 47% patients developed this complication. Compared with nondiabetics, PTDM patients were significantly older (P = .000), more obese (P = .002), received tacrolimus (P = .027), and had hypertension (P = .014) or cardiovascular events (P = .000). Serum creatinine and hepatitis C virus infection rated were similar in both groups. On multivariate analyses, the risk factors significantly associated with the development of PTDM were greater age (P = .0024), obesity (P = .0032), and hypertension (P = .0516).

CONCLUSIONS

Half of the patients with PTDM developed new-onset diabetes within the first 3 months. Age, obesity, and hypertension were among the risk factors for diabetes posttransplantation. After the transplantation, the modifiable risk factors are control of body weight and control of hypertension.

The timely construction of arteriovenous fistulae: a key to reducing morbidity and mortality and to improving cost management

BACKGROUND

Some investigators have shown that the initial placement of a catheter or graft, instead of the timely construction of an arteriovenous fistula (AVF), late referral to nephrology services and unplanned dialysis increase morbidity and mortality in chronic haemodialysis (CHD) patients. Furthermore, a delay in providing an adequate AVF entails significant increases in treatment-related costs. This study was limited to the analysis of the effects of the lack of an adequate vascular access for CHD on morbidity and mortality.

METHODS

According to the vascular access they had in the first 3 months of CHD treatment 96 patients were divided into three groups (VA group): Group 1 (G1), having an adequate AVF in the first 3 months; Group 2 (G2), starting with a catheter but finishing with an AVF; and Group 3 (G3) starting and finishing with a catheter. Time-dependent Cox regression analysis was performed to identify variables associated with survival, and the standardized mortality index (SMI) was calculated. Finally, we studied cost-effectiveness.

RESULTS

Time-dependent Cox regression and logistic regression analyses showed the statistically significant variable to be the VA group. To ensure that mortality was comparable between VA groups, eliminating age bias, the findings were adjusted applying SMI. G1 patients appear to have a lesser risk of death (relative risk, 0.39) than G2 and G3 patients, as do G2 relative to G3 patients. Also, after adjustment with SMI, patients over 65 years, presumably at greater risk of death, have a lower mortality than the <or=65 age group. Patients with an adequate and functioning AVF lived longer than the others, and the cost of each 'death prevented' was lower (3318/patient).

CONCLUSIONS

The lack of an adequate AVF at the start of haemodialysis decreases survival significantly-even if patients are not diabetic, are referred to a nephrologist early and planned haemodialysis is initiated. It also increases the cost of each prevented death.

Factors associated with erectile dysfunction in male kidney transplant recipients

A transversal study was carried out in order to evaluate the prevalence of erectile dysfunction (ED) in adult kidney transplant patients of our region (N=243), and to investigate the sociodemographic, analytic, and clinical factors associated with it. To evaluate ED, the Spanish five items version of the International Index of Erectile Function (IIEF-5) was employed. Sociodemographic, analytic, and clinical data, including 12 cardiovascular risk factors, were also collected. A total of 199 patients (82%) were included. The median age was 52 y (43-62 y); 106 patients (54.9%) presented with ED. Variables associated with ED were: higher age; longer time on dialysis prior to transplantation; higher comorbidity; presence of diabetes mellitus; had undergone prostatic surgery or peripheric artheriopathy; lower diastolic pressure; and some anti hypertensive drugs. Logistic Regression Model performed step by step showed (R(2)=0.52) that factors independently associated with ED were: age, time on dialysis previous to transplant, and peripheric artheriopathy.

Quality of life of patients with chronic renal allograft rejection and anemia

BACKGROUND

The treatment with recombinant human erythropoietin (rHuEPO) of anemia associated with renal insufficiency (RI) improves the health-related quality of life (HRQOL) of those patients. The objective of this study was to evaluate the HRQOL of patients with chronic allograft nephropathy (CAN) and anemia associated to RI, and the effect of rHuEPO treatment on the HRQOL.

METHODS

This prospective study consisted of 17 kidney transplant patients with RI caused by CAN and anemia who received rHuEPO. The hemoglobin (Hb) target was 12 g/dL. Serum Hb, hematocrit (Hct) and creatinine clearance (CrCl) were collected. HRQOL was evaluated with the Kidney Disease Quality of Life Short-Form 36 (SF-36) questionnaire at the start, at the 3rd and 6th month and at the end of the follow-up. SF-36 scores (eight scales, physical component summary (PCS) and mental component summary (MCS) were standardized by age and gender using the Spanish population norms. The "effect size" was also calculated for each score.

RESULTS

Hb and Hct statistically improved from the start to the 3rd month and to the end of the study (p<0.01). Although the CrCl remained stable during most of the follow-up, it worsened (p=0.002) around the 13th month. SF-36 scores at the beginning were worse than that of the general population. Three SF-36 scales statistically improved; role-physical, vitality and mental health. The effect size was moderate for pain (0.41), role-emotional (0.39) and MCS (0.42); and large for role-physical (0.65), vitality (0.81) and mental health (0.74).

CONCLUSIONS

The poor HRQOL of patients with CAN and anemia improves with rHuEPO treatment, the effect size varying from moderate to large.

Influence of erectile dysfunction on health related quality of life of male kidney transplant patients

The objective of the present study was to investigate if a psychological adaptation capacity exists in kidney transplant bearers, even with ageing, in relation to erectile dysfunction (ED). We studied ED using IIEF-5 and health-related quality of life (HRQoL) using the SF-36 Health Survey, in a large sample of male renal transplant patients (n=242), searching for the influence of ED on HRQoL. Patients included 199 patients (82%); the median age was 52 y (43-62); 106 patients (54.9%) presented ED. These patients were divided into four groups according to median age. SF-36 scores were worse for ED vs non-ED patients in the first three age groups, but not in age group 4. SF-36 Mental Component Summary was similar for patients with ED and without ED in all age groups. We confirm the hypothesis that a psychological adaptation occurs in renal transplant patients in all age groups, when suffering ED.

Spanish validation of the "kidney transplant questionnaire": a useful instrument for assessing health related quality of life in kidney transplant patients

BACKGROUND

There is a growing interest in the evaluation of Health Related Quality of Life (HRQoL) among patients undergoing Renal Replacement Therapy. In Spain, no specific questionnaire exists for kidney transplant patients. Here we present the Spanish validation of the first specific HRQoL assessment tool: the kidney transplant questionnaire (KTQ).

METHODS

Prospective study of 31 patients on transplant waiting list who received the first kidney. Patients were evaluated before transplant and after 1, 3, 6 and 12 months, using the KTQ and the SF-36 Health Survey. Feasibility, validity, reliability, and sensibility to change were evaluated.

RESULTS

Mean time of administration of the KTQ was 12 minutes. Correlation coefficients among KTQ dimensions range between 0.32 and 0.72. Correlation coefficients of KTQ dimensions with SF-36 PCS were low (r<0.4), and with SF-36 MCS were moderate-high (r>0.4) except for Physical Symptom dimension (r = 0.33). Cronbach's Alpha was satisfactory for all KTQ dimensions (Physical Symptoms = 0.80; Fatigue = 0.93; Uncertainty/Fear = 0.81; Emotional= 0.90) except Appearance (0.69). Intraclass correlation coefficients ranged between 0.63 and 0.85, similar to those of the original KTQ version.

CONCLUSIONS

Results of validation study show that feasibility, validity, reliability and sensibility to change of the Spanish version of the KTQ are similar to those of the original version.

Biochemical basis for the hypercoagulable state seen in Cushing syndrome; discussion 1006-7

HYPOTHESIS

Cushing syndrome (CS) is associated with a hypercoagulable state that results in a 4-fold increase in the incidence of pulmonary embolism, deep venous thrombosis, and a 4-fold mortality rate compared with the general population. The incidence of CS in humans is approximately 2 to 5 per million per year, whereas in dogs it is much higher. The clinical complications of CS in humans are also manifested in dogs. We used a dog model of CS to better define the biochemical basis for the hypercoagulable state seen in the disease.

DESIGN

A consecutive sample of dogs with CS and a cohort of healthy control dogs identified at a "well-dog check" were enrolled. All dogs underwent blood assays to identify the levels of procoagulant factors, natural antithrombotics, and the degree of ongoing activation of the coagulation cascade.

SETTING

University veterinary medical teaching hospital.

RESULTS

A total of 86 dogs were enrolled, 56 with CS and 30 control dogs. Levels of procoagulation factors II, V, VII, IX, X, XII, and fibrinogen were significantly increased in dogs with CS (P<.05). The natural antithrombotic antithrombin was significantly decreased in dogs with CS (P<.02). Thrombin-antithrombin complexes, a marker of subclinical thrombosis, were significantly increased in dogs with CS (P<.05).

CONCLUSIONS

The hypercoagulable state of CS is demonstrated by an increase in thrombin-antithrombin complexes. This hypercoagulable state may be caused in part by (1) an elevation of procoagulant factors, and (2) a decrease in antithrombin. Because of the similar clinical and biochemical changes between dogs with CS and humans, this canine model may be a useful tool for the future study of the hypercoagulable state in CS.

Vasodilatory effect in rat aorta of eriodictyol obtained from Satureja obovata

The vasodilator effect of eriodictyol (5,7,3',4'-tetrahydroxyflavanone), isolated previously from the medicinal plant Satureja obovata Lag., was studied in rat thoracic aorta rings. Eriodictyol relaxed in a concentration-dependent manner the noradrenaline (10(-6) M) and KCl (80 mM) induced contractions. The relaxant effect was more potent in noradrenaline precontracted preparations (IC50 = 6.11 +/- 0.2 x 10(-5) M) than in those precontracted with KCl (IC50 = 2.96 +/- 0.1 x 10(-4) M). Eriodictyol produced weakly concentration-dependent inhibition of the phasic component induced by KCl and noradrenaline while the inhibition of the tonic phase of these contractions was more pronounced. These effects were endothelium independent. In addition, eriodictyol (10(-5) and 5 x 10(-5) M) inhibited CaCl2 cumulative concentration response curves. Eriodictyol weakly inhibited the release of calcium from the sarcoplasmic reticulum and its contribution to the relaxant effect seems to be slight. We have also observed the relaxant effect of eriodictyol on phorbol-12-myristate-13-acetate (PMA) (10(-7) M) induced contractions both in normal calcium (IC50 = 4.69 +/- 0.3 x 10(-5) M) and calcium-free medium (IC50 = 3.74 +/- 0.4 x 10(-5) M). Finally we studied the effects on protein kinase C (PKC) activity. This flavonoid did not show any activity. These results suggest that the vasodilator effect of eriodictyol in rat thoracic aorta could be partially related to the inhibition of calcium influx or other enzymatic protein subsequent to activation of PKC related to the activation of contractile proteins like myosin light chain kinase (MLCK).

Antiinflammatory and antioxidant activity of plants used in traditional medicine in Ecuador

Ethanolic extracts from 15 plant species, representing eight different families, used in traditional medicine in Ecuador were evaluated for antiinflammatory and antioxidant activities. Conyza floribunda, Eupatorium articulatum, Bonafousia longituba, Bonafousia sananho, Tagetes pusilla and Piper lenticellosum extracts showed a significant antiinflammatory activity in vivo in the carrageenan-induced paw oedema model in mice. The extracts were also tested in vitro for their ability to inhibit lipid peroxidation and to scavenge superoxide and hydroxyl radicals. E. articulatum extract possesses both activities. Baccharis trinervis, E. articulatum and Phytolacca rivinoides extracts were active as antioxidants.

Modulation of angiotensin-converting enzyme by nitric oxide

1. The aim of the present study was to determine the effect of nitric oxide (NO) on angiotensin-converting enzyme (ACE) activity. 2. A biochemical study was performed in order to analyse the effect of the NO-donors, SIN-1 and diethylamine/NO (DEA/NO), and of an aqueous solution of nitric oxide on the ACE activity in plasma from 3-month old male Sprague-Dawley rats and on ACE purified from rabbit lung. SIN-1 significantly inhibited the activity of both enzymes in a concentration-dependent way between 1 and 100 microM. DEA/NO inhibited the activity of purified ACE from 0.1 microM to 10 microM and plasma ACE, with a lower potency, between 1 and 100 microM. An aqueous solution of NO (100 and 150 microM) also inhibited significantly the activity of both enzymes. Lineweaver-Burk plots indicated an apparent competitive inhibition of Hip-His-Leu hydrolysis by NO-donors. 3. Modulation of ACE activity by NO was also assessed in the rat carotid artery by comparing contractions elicited by angiotensin I (AI) and AII. Concentration-response curves to both peptides were performed in arteries with endothelium in the presence of the guanylyl cyclase inhibitor, ODQ (10 microM), and the inhibitor of NO formation, L-NAME (0.1 mM). NO, which is still released from endothelium in the presence of 10 microM ODQ, elicited a significant inhibition of AI contractions at low concentrations (1 and 5 nM). In the absence of endothelium, 1 microM SIN-1 plus 10 microM ODQ, as well as 10 microM DEA/NO plus 10 microM ODQ induced a significant inhibition on AI-induced contractions at 1 and 5 nM and at 1-100 nM, respectively. 4. In conclusion, we demonstrated that (i) NO and NO-releasing compounds inhibit ACE activity in a concentration-dependent and competitive way and that (ii) NO release from endothelium physiologically reduces conversion of AI to AII.

Different mechanisms involved in the vasorelaxant effect of flavonoids isolated from Satureja obovata

The inhibitory effects of naringenin, eriodictyol, and luteolin (10(-5) and 5 x 10(-5) M), previously isolated from Satureja obovata subsp. obovata var. valentina (Lamiaceae), on rat thoracic aorta were investigated. Flavonoids at the two concentrations assayed (10(-5) and 5 x 10(-5) M) showed different smooth muscle relaxant behaviour in the three phases involved in the noradrenaline (10(-6) M)-induced contractions. The three flavonoids showed an inhibitory effect of the phasic component in order of potency: luteolin > eriodictyol > naringenin. Luteolin and eriodictyol inhibited both tonic-I and tonic-II phases associated to the inhibition of PKC and calcium influx, respectively, whereas naringenin only inhibited the tonic-I phase associated to inhibition of PKC.