Diuretics and bioimpedance-measured fluid spaces in hypertensive patients

The authors examined the relationship between thiazide-type diuretics and fluid spaces in a cohort of hypertensive patients in a retrospective study of 60 stable hypertensive patients without renal abnormalities who underwent whole-body bioimpedance analysis. Overhydration was greater in the diuretic group, but only to a nonsignificant degree (5.9 vs. 2.9%; P=.21). The total body water did not differ in the two groups (41.8 L vs. 40.5 L; P=.64). Extracellular fluid volume (ECV) (19.7 L vs. 18.5 L; P=.35) and intracellular fluid volume (ICV) spaces (20.8 L vs. 21.3 L; P=.75) were also not significantly different in the two groups. The ratio of ICV:ECV, however, appeared different: 1.05 vs 1.15 (P=.017) and the effect was maintained in the linear regression-adjusted model (β coefficient: -0.143; P=.001). The diuretic-related distortion of ICV:ECV ratio indicates potential fluid redistribution in hypertensive patients, with ICV participating in the process.

Potentiality of the "Gum Metal" titanium-based alloy for biomedical applications

In this study, the "Gum Metal" titanium-based alloy (Ti-23Nb-0.7Ta-2Zr-1.2O) was synthesized by melting and then characterized in order to evaluate its potential for biomedical applications. Thus, the mechanical properties, the corrosion resistance in simulated body fluid and the in vitro cell response were investigated. It was shown that this alloy presents a very high strength, a low Young's modulus and a high recoverable strain by comparison with the titanium alloys currently used in medicine. On the other hand, all electrochemical and corrosion parameters exhibited more favorable values showing a nobler behavior and negligible toxicity in comparison with the commercially pure Ti taken as reference. Furthermore, the biocompatibility tests showed that this alloy induced an excellent response of MC3T3-E1 pre-osteoblasts in terms of attachment, spreading, viability, proliferation and differentiation. Consequently, the "Gum Metal" titanium-based alloy processes useful characteristics for the manufacturing of highly biocompatible medical devices.

FT-IR spectroscopy as a sentinel technology in earthworm toxicology

FT-IR spectroscopy is a useful tool for determining the biomolecular profile of micro-samples of body fluids such as coelomic fluid of earthworms. The present study focuses on the usefulness of the earthworm (Perionyx sansibaricus) coelomic fluid for observing pathologically induced biochemical changes. Compared to controls, appreciable changes in expression of peaks were observed in worms exposed to seven selected xenobiotics (pesticides, heavy metals, herbicides and detergents). Observation of bands in the region 1600-1690 cm(-1) indicates the presence of amide I band in all the worms. The peak at 2364 cm(-1) present as a weak band on day 7 of treatment, is shifted to 2358/2359 cm(-1) and more pronounced in most of the treated groups on day 14. Presence of band at 1663 cm(-1) in controls is attributed to CO stretching vibration representing the amino acid, glutamic acid. Under toxicological conditions vibration in this region is absent. Presence of the amino acid arginine (1633 cm(-1)) and lysine (1629 cm(-1)) and absence of glutamic acid (1663 cm(-1)) under toxicological stress were characteristic. FT-IR spectra of the coelomic fluid were similar under the sublethal and lethal concentrations of the test chemicals. The potential use of FT-IR spectral information as baseline data for toxicological studies and for monitoring the quality of the environment is recommended.

Oral factors affecting titanium elution and corrosion: an in vitro study using simulated body fluid

Objectives

Ti, which is biocompatible and resistant to corrosion, is widely used for dental implants, particularly in patients allergic to other materials. However, numerous studies have reported on Ti allergy and the in vitro corrosion of Ti. This study investigated the conditions that promote the elution of Ti ions from Ti implants.

Methods

Specimens of commercially pure Ti, pure nickel, a magnetic alloy, and a gold alloy were tested. Each specimen was immersed in a simulated body fluid (SBF) whose pH value was controlled (2.0, 3.0, 5.0, 7.4, and 9.0) using either hydrochloric or lactic acid. The parameters investigated were the following: duration of immersion, pH of the SBF, contact with a dissimilar metal, and mechanical stimulus. The amounts of Ti ions eluted were measured using a polarized Zeeman atomic absorption spectrophotometer.

Results

Eluted Ti ions were detected after 24 h (pH of 2.0 and 3.0) and after 48 h (pH of 9.0). However, even after 4 weeks, eluted Ti ions were not detected in SBF solutions with pH values of 5.0 and 7.4. Ti elution was affected by immersion time, pH, acid type, mechanical stimulus, and contact with a dissimilar metal. Elution of Ti ions in a Candida albicans culture medium was observed after 72 h.

Significance

Elution of Ti ions in the SBF was influenced by its pH and by crevice corrosion. The results of this study elucidate the conditions that lead to the elution of Ti ions in humans, which results in implant corrosion and Ti allergy.

Inhibiting the growth of pancreatic adenocarcinoma in vitro and in vivo through targeted treatment with designer gold nanotherapeutics

Background

Pancreatic cancer is one of the deadliest of all human malignancies with limited options for therapy. Here, we report the development of an optimized targeted drug delivery system to inhibit advanced stage pancreatic tumor growth in an orthotopic mouse model.

Method/Principal Findings

Targeting specificity in vitro was confirmed by preincubation of the pancreatic cancer cells with C225 as well as Nitrobenzylthioinosine (NBMPR - nucleoside transporter (NT) inhibitor). Upon nanoconjugation functional activity of gemcitabine was retained as tested using a thymidine incorporation assay. Significant stability of the nanoconjugates was maintained, with only 12% release of gemcitabine over a 24-hour period in mouse plasma. Finally, an in vivo study demonstrated the inhibition of tumor growth through targeted delivery of a low dose of gemcitabine in an orthotopic model of pancreatic cancer, mimicking an advanced stage of the disease.

Conclusion

We demonstrated in this study that the gold nanoparticle-based therapeutic containing gemcitabine inhibited tumor growth in an advanced stage of the disease in an orthotopic model of pancreatic cancer. Future work would focus on understanding the pharmacokinetics and combining active targeting with passive targeting to further improve the therapeutic efficacy and increase survival.

Beneficial role of tolvaptan in the control of body fluids without reductions in residual renal function in patients undergoing peritoneal dialysis

The V2 receptor antagonist tolvaptan has been approved for volume control in heart-failure patients in Japan. Tolvaptan increases renal blood flow, and so the present study was designed to ascertain whether tolvaptan could be a useful diuretic for volume control without reducing residual renal function (RRF) in peritoneal dialysis (PD) patients. Tolvaptan was administered in 15 PD patients (15 mg daily). Urine volume, body weight, and blood pressure were monitored Urinary excretion of urea nitrogen Na+, the osmolality of plasma and urine, and peritoneal and renal Kt/V were analyzed before and after tolvaptan treatment. In 11 of 15 patients, urine volume increased to more than 400 mL daily. A significant increase in diluted urine was observed, as indicated by a reduction in the specific gravity or osmolality of urine (or both). Urinary excretion of urea nitrogen, and Na+ was significantly increased Increases in renal Kt/V were observed, but peritoneal Kt/V was unchanged. Singnificant increase in creatinine clearance was also observed These data suggest that tolvaptan not only stimulates water diuresis, but also natriuresis, without reducing RRF in PD patients. Hence, tolvaptan could be a beneficial tool for the control of body fluid and maintenance of RRF in PD patients.

Limited relationship between cervico-vaginal fluid cytokine profiles and cervical shortening in women at high risk of spontaneous preterm birth

Objective

To determine the relationship between high vaginal pro-inflammatory cytokines and cervical shortening in women at high risk of spontaneous preterm labor and to assess the influence of cervical cerclage and vaginal progesterone on this relationship.

Methods

This prospective longitudinal observational study assessed 112 women with at least one previous preterm delivery between 16 and 34 weeks’ gestation. Transvaginal cervical length was measured and cervico-vaginal fluid sampled every two weeks until 28 weeks. If the cervix shortened (<25 mm) before 24 weeks’ gestation, women (cases) were randomly assigned to cerclage or progesterone and sampled weekly. Cytokine concentrations were measured in a subset of cervico-vaginal fluid samples (n = 477 from 78 women) by 11-plex fluid-phase immunoassay.

Results

All 11 inflammatory cytokines investigated were detected in cervico-vaginal fluid from women at high risk of preterm birth, irrespective of later cervical shortening. At less than 24 weeks’ gestation and prior to intervention, women destined to develop a short cervix (n = 36) exhibited higher cervico-vaginal concentrations than controls (n = 42) of granulocyte-macrophage colony-stimulating factor [(GM-CSF) 16.2 fold increase, confidence interval (CI) 1.8–147; p = 0.01] and monocyte chemotactic protein-1 [(MCP-1) 4.8, CI 1.0–23.0; p = 0.05]. Other cytokines were similar between cases and controls. Progesterone treatment did not suppress cytokine concentrations. Interleukin (IL)-6, IL-8, granulocyte colony-stimulating factor (G-CSF), interferon (IFN)-γ and tumour necrosis factor (TNF)-α concentrations were higher following randomization to cerclage versus progesterone (p<0.05). Cerclage, but not progesterone treatment, was followed by a significant increase in cervical length [mean 11.4 mm, CI 5.0–17.7; p<0.001].

Conclusions

Although GM-CSF and MCP-1 cervico-vaginal fluid concentrations were raised, the majority of cervico-vaginal cytokines did not increase in association with cervical shortening. Progesterone treatment showed no significant anti-inflammation action on cytokine concentrations. Cerclage insertion was associated with an increase in the majority of inflammatory markers and cervical length.

Biomolecular coronas provide the biological identity of nanosized materials

The search for understanding the interactions of nanosized materials with living organisms is leading to the rapid development of key applications, including improved drug delivery by targeting nanoparticles, and resolution of the potential threat of nanotechnological devices to organisms and the environment. Unless they are specifically designed to avoid it, nanoparticles in contact with biological fluids are rapidly covered by a selected group of biomolecules to form a corona that interacts with biological systems. Here we review the basic concept of the nanoparticle corona and its structure and composition, and highlight how the properties of the corona may be linked to its biological impacts. We conclude with a critical assessment of the key problems that need to be resolved in the near future.

Magnesium alloys as body implants: fracture mechanism under dynamic and static loadings in a physiological environment

It is essential that a metallic implant material possesses adequate resistance to cracking/fracture under the synergistic action of a corrosive physiological environment and mechanical loading (i.e. stress corrosion cracking (SCC)), before the implant can be put to actual use. This paper presents a critique of the fundamental issues with an assessment of SCC of a rapidly corroding material such as magnesium alloys, and describes an investigation into the mechanism of SCC of a magnesium alloy in a physiological environment. The SCC susceptibility of the alloy in a simulated human body fluid was established by slow strain rate tensile (SSRT) testing using smooth specimens under different electrochemical conditions for understanding the mechanism of SCC. However, to assess the life of the implant devices that often possess fine micro-cracks, SCC susceptibility of notched specimens was investigated by circumferential notch tensile (CNT) testing. CNT tests also produced important design data, i.e. threshold stress intensity for SCC (KISCC) and SCC crack growth rate. Fractographic features of SCC were examined using scanning electron microscopy. The SSRT and CNT results, together with fractographic evidence, confirmed the SCC susceptibility of both smooth and notched specimens of a magnesium alloy in the physiological environment.

Bioactive silica-based drug delivery systems containing doxorubicin hydrochloride: in vitro studies

This study reports the applicability of sol-gel derived silica and silica-polydimethylsiloxane (silica-PDMS) composites as a potential bioactive implantable drug delivery system for doxorubicin hydrochloride (DOX). These composites also contain calcium chloride (CaCl(2)) and triethylphosphate as precursors of Ca(2+) and (PO(4))(3-) ions. These composites were immersed for 20 days in a simulated body fluid (SBF) at 37°C to study the release rate of the DOX, dissolution of the silica and the formation of hydroxyapatite on the composites' surface. The results show that the release rate of the DOX can be effectively tailored by either the addition of a polydimethylsiloxane (PDMS), or by varying the amount of CaCl(2), where the elution rate of DOX increases with increasing amount of the CaCl(2) precursor. Importantly, irrespective of the amount of CaCl(2), no burst release of DOX has been observed in any of the silica-PDMS system investigated. On the other hand, a slow release of DOX has been observed with a trend that followed a zero (0)-order kinetics for a total of 20 days of elusion. The dissolution of silica in SBF was ca. two-times faster than that of silica-PDMS, with the former reaching an average saturation level of 80 μg/mL whilst the latter reached 46 μg/mL within 20 days. Both the silica and the silica-PDMS composites show bioactivity i.e. they absorb calcium phosphate from SBF. Within 10 days, a ten-fold increase in the concentration of calcium phosphate deposit has been observed on the silica-PDMS relative to the silica. The constant rates of DOX release observed for the silica-PDMS composites indicate that the calcium phosphate deposit do not obstruct controlled release of the drug.

Direct ex vivo measurement of the fluid permeability of loose scar tissue

Fluid flow is important in many biomechanical models, but there is a lack of experimental data that quantifies soft tissue permeability. We measured the tissue permeability in fibrous soft tissue, using a novel technique to obtain specimens by allowing soft tissue to grow into coralline hydroxyapatite scaffoldings implanted between the abdominal muscle layers of rats.

Non-invasive biological fluid matrices analysed to assess exposure to environmental tobacco smoke

Human biomonitoring (analysis of biological fluids) is increasingly being used for assessing exposure to environmental pollutants. Smoking tobacco is a significant source of indoor air pollution and is harmful to human health. The aim of this research was to find both the best non-invasive matrices (from among saliva, urine, semen and sweat) for evaluating environmental exposure to tobacco smoke and the relationships between thiocyanates (biomarkers of environmental tobacco smoke exposure) and other inorganic ions in these matrices collected from active and passive smokers and also non-smokers.

Body fluid expansion in acromegaly is related to enhanced epithelial sodium channel (ENaC) activity

BACKGROUND

Soft-tissue swelling and increased extracellular volume, two features of acromegaly, are related to the antinatriuretic effects of excess GH/IGF-I, but the precise pathophysiological mechanism is unclear.

OBJECTIVE

Our objective was to determine the effect of the GH excess on renal and extrarenal epithelial sodium channel (ENaC) activity.

DESIGN AND SETTING

We conducted a prospective randomized open-label blinded-endpoint (PROBE) crossover study (www.ClinicalTrials.gov Identifier: NCT00531908) at a tertiary referral medical center and clinical investigation center.

INTERVENTION

Sixteen patients (five females, 11 males) with acromegaly were randomly assigned to receive 20 mg amiloride (an ENaC blocker) and 25 mg furosemide (a Na-K-2Cl cotransporter blocker) under a high-sodium diet to suppress endogenous renin and aldosterone.

MEASUREMENTS

Diuretic-induced changes in the urinary Na/K ratio (reflecting coupling between ENaC-mediated Na reabsorption and distal K secretion) and the intranasal amiloride-sensitive potential (reflecting extrarenal ENaC activity) were measured before and 6 months after (range, 1-12 months) treatment of acromegaly.

RESULTS

Serum IGF-I concentrations normalized in all the patients after treatment of acromegaly. Baseline plasma renin and aldosterone concentrations remained unchanged after treatment. Active acromegaly, compared with controlled disease, was associated with an enhanced response [median (interquartile range)] to amiloride [urinary Na/K, 13.9 (9.8-19.5) vs. 6.3 (4.3-8.4) mmol/mmol, P = 0.0003], a reduced response to furosemide [urinary Na/K, 5.2 (4.6-7.2) vs. 7.1 (5.4-8.8) mmol/mmol, P =0.0151], and an increased intranasal amiloride-sensitive potential [5.8 (11.9-3.8) vs. 4.2 (6.4-2.1) mV, P = 0.031], respectively.

CONCLUSION

GH/IGF-I excess in humans is associated with enhanced renal and extrarenal ENaC activity that may contribute to soft-tissue swelling and volume expansion in acromegaly.

The activity of antimicrobial peptide S-thanatin is independent on multidrug-resistant spectrum of bacteria

In this study, the activity of S-thanatin (an analog of antimicrobial peptide derived from thanatin) against different bacterial pathogens frequently which can cause therapeutic problems was tested. The result showed minimal inhibitory concentrations (MICs) of S-thanatin against all isolates of the Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, Enterobacter aerogenes, Klebsiella ornithinolytica and Klebsiella oxytoca were in the range of 4-16μg/ml, no matter which antibiotic the bacterial was resistant or susceptible, while almost all MICs to Gram-positive bacterial were >128μg/ml except Enterococcus faecium. S-thanatin was more effective toward Gram-negative strains, especially for Enterobacter and Klebsiella. The MICs of S-thanatin were no significantly different in the same species regardless of antibiotic sensitive or -resistant isolates to single or multiple antibiotic (P>0.05). Likewise, no notable difference could be observed between E. coli, K. pneumoniae, E. cloacae, E. aerogenes, K. ornithinolytica which were sensitive to S-thanatin (P>0.05). It was implied that the antimicrobial activity of S-thanatin was independent on multi-drug resistance spectrum of bacteria.

A comparative study of mesoporous glass/silk and non-mesoporous glass/silk scaffolds: physiochemistry and in vivo osteogenesis

Mesoporous bioactive glass (MBG) is a new class of biomaterials with a well-ordered nanochannel structure, whose in vitro bioactivity is far superior than that of non-mesoporous bioactive glass (BG); the material's in vivo osteogenic properties are, however, yet to be assessed. Porous silk scaffolds have been used for bone tissue engineering, but this material's osteoconductivity is far from optimal. The aims of this study were to incorporate MBG into silk scaffolds in order to improve their osteoconductivity and then to compare the effect of MBG and BG on the in vivo osteogenesis of silk scaffolds. MBG/silk and BG/silk scaffolds with a highly porous structure were prepared by a freeze-drying method. The mechanical strength, in vitro apatite mineralization, silicon ion release and pH stability of the composite scaffolds were assessed. The scaffolds were implanted into calvarial defects in SCID mice and the degree of in vivo osteogenesis was evaluated by microcomputed tomography (μCT), hematoxylin and eosin (H&E) and immunohistochemistry (type I collagen) analyses. The results showed that MBG/silk scaffolds have better physiochemical properties (mechanical strength, in vitro apatite mineralization, Si ion release and pH stability) compared to BG/silk scaffolds. MBG and BG both improved the in vivo osteogenesis of silk scaffolds. μCT and H&E analyses showed that MBG/silk scaffolds induced a slightly higher rate of new bone formation in the defects than did BG/silk scaffolds and immunohistochemical analysis showed greater synthesis of type I collagen in MBG/silk scaffolds compared to BG/silk scaffolds.

In vitro studies of biomedical magnesium alloys in a simulated physiological environment: a review

In spite of the immense potential of biodegradable magnesium alloys, the fast degradation rates of Mg-based biomedical implants in the physiological environment impose severe limitations in many clinical applications. Consequently, extensive in vitro studies have been carried out to investigate the materials' performance and fathom the associated mechanisms. Here, an up-to-date review of the in vitro studies on biomedical magnesium alloys in a simulated physiological environment is provided. This review focuses on four topics: (1) materials selection and in vitro biocompatibility of biomedical magnesium alloys; (2) in vitro degradation of biomedical magnesium alloys in simulated physiological environments, specifically discussing corrosion types, degradation rates, corrosion products and impact of the constituents in body fluids on materials degradation; (3) selection of suitable test media for in vitro assessment; and (4) future research trends.

Elucidating mechanisms of chlorine toxicity: reaction kinetics, thermodynamics, and physiological implications

Industrial and transport accidents, accidental releases during recreational swimming pool water treatment, household accidents due to mixing bleach with acidic cleaners, and, in recent years, usage of chlorine during war and in acts of terror, all contribute to the general and elevated state of alert with regard to chlorine gas. We here describe chemical and physical properties of Cl(2) that are relevant to its chemical reactivity with biological molecules, including water-soluble small-molecular-weight antioxidants, amino acid residues in proteins, and amino-phospholipids such as phosphatidylethanolamine and phosphatidylserine that are present in the lining fluid layers covering the airways and alveolar spaces. We further conduct a Cl(2) penetration analysis to assess how far Cl(2) can penetrate the surface of the lung before it reacts with water or biological substrate molecules. Our results strongly suggest that Cl(2) will predominantly react directly with biological molecules in the lung epithelial lining fluid, such as low-molecular-weight antioxidants, and that the hydrolysis of Cl(2) to HOCl (and HCl) can be important only when these biological molecules have been depleted by direct chemical reaction with Cl(2). The results from this theoretical analysis are then used for the assessment of the potential benefits of adjuvant antioxidant therapy in the mitigation of lung injury due to inhalation of Cl(2) and are compared with recent experimental results.

In vitro biocompatibility and corrosion resistance of a new implant titanium base alloy

One objective of this work was to study the corrosion resistance of the new implant Ti-10Zr-5Ta-5Nb alloy in physiological fluids of different pH values, simulating the extreme functional conditions. Another objective was in vitro biocompatibility evaluation of the new alloy using human fetal osteoblast cell line hFOB 1.19. Cytocompatibility was assessed by determination of possible material cytotoxic effects, cell morphology and cell adhesion. The thermo-mechanical processing of the new implant alloy consisted in plastic deformation (almost 90%) performed by hot rolling accompanied by an initial and final heat treatment. The new Ti-10Zr-5Ta-5Nb alloy presented self-passivation, with a large passive potential range and low passive current densities, namely, a very good anticorrosive resistance in Ringer solution of acid, neutral and alkaline pH values. Cell viability was not affected by the alloy substrate presence and a very good compatibility was noticed.

Effect of beta3-adrenergic agonists on alveolar fluid clearance in hypoxic rat lungs

BACKGROUND

Recent research suggests that beta(2)-adrenergic agonists increase alveolar fluid clearance (AFC) under physiologic and pathologic conditions. It is unknown whether beta(3)-adrenergic agonists also increase AFC under pathologic conditions. The aim of this study was to investigate the effect of beta(3)-adrenergic agonists on AFC following hypoxic lung injury and the mechanisms involved.

METHODS

Hypoxic rats were exposed to 10% oxygen. BRL-37344 (beta(3)-adrenergic agonist) or CGP-12177 (selective beta(3)-adrenergic agonist) alone or combined with beta receptor antagonists, sodium channel blockers, or Na(+)/K(+)-ATPase blockers were perfused into the alveolar space of rats exposed to 10% oxygen for 48 hours. Total lung water content (TLW) and AFC were measured.

RESULTS

AFC did not change for the first 24 hours but then decreased after 48-hour exposure to 10% oxygen. The perfusion of BRL-37344 or CGP-12177 significantly increased AFC in normal and hypoxic rats. The AFC-stimulating effect of CGP-12177 was lowered with amiloride (a Na(+) channel blocker) and ouabain (a Na(+)/K(+)-ATPase inhibitor) by 37% and 49%, respectively. Colchicine significantly inhibited the effect of CGP-12177.

CONCLUSIONS

These findings suggest that beta(3)-adrenergic agonists can increase AFC during hypoxic lung injury in rats and accelerate the amelioration of pulmonary edema.

IFN{gamma} regulates retinal pigment epithelial fluid transport

The present experiments show that IFNgamma receptors are mainly localized to the basolateral membrane of human retinal pigment epithelium (RPE). Activation of these receptors in primary cultures of human fetal RPE inhibited cell proliferation and migration, decreased RPE mitochondrial membrane potential, altered transepithelial potential and resistance, and significantly increased transepithelial fluid absorption. These effects are mediated through JAK-STAT and p38 MAPK signaling pathways. Second messenger signaling through cAMP-PKA pathway- and interferon regulatory factor-1-dependent production of nitric oxide/cGMP stimulated the CFTR at the basolateral membrane and increased transepithelial fluid absorption. In vivo experiments using a rat model of retinal reattachment showed that IFNgamma applied to the anterior surface of the eye can remove extra fluid deposited in the extracellular or subretinal space between the retinal photoreceptors and RPE. Removal of this extra fluid was blocked by a combination of PKA and JAK-STAT pathway inhibitors injected into the subretinal space. These results demonstrate a protective role for IFNgamma in regulating retinal hydration across the outer blood-retinal barrier in inflammatory disease processes and provide the basis for possible therapeutic interventions.

Influence of oxygen, albumin and pH on copper dissolution in a simulated uterine fluid

OBJECTIVES

The aim of this paper is to study the influence of albumin content, from 5 to 45 g/L, on copper dissolution and compounds composition in a simulated uterine solution.

METHODS

Experiments were performed in atmospheric pressure conditions and with an additional oxygen pressure of 0.2 atmospheres, at 6.3 and 8.0 pH values, and at a temperature of 37 +/- 0.1 degrees C for 1, 3, 7, and 30 days experimentation time.

RESULTS

The copper dissolution rate has been determined using absorbance measurements, finding the highest value for pH 8.0, 35 g/L albumin, and with an additional oxygen pressure of 0.2 atmospheres: 674 microg/day for 1 day, and 301 microg/day for 30 days. X-ray photoelectron spectroscopy (XPS) results show copper(II) as the main copper oxidation state at pH 8.0; and copper(I) and metallic copper at pH 6.3.

CONCLUSIONS

The presence of albumin up to 35 g/L, accelerates copper dissolution. For high albumin content a stabilisation on the copper dissolution takes place. Corrosion product layer morphology is poorly protective, showing paths through which copper ions can release.

The effects of chronic inorganic and organic phosphate exposure on bactericidal activity of the coelomic fluid of the sea urchin Lytechinus variegatus (Lamarck) (Echinodermata: Echinoidea)

The sea urchin Lytechinus variegatus can survive chronic exposure to sodium phosphate (inorganic phosphate) concentrations as high as 3.2 mg L-1, and triethyl phosphate (organic phosphate) concentrations of 1000 mg L-1. However, chronic exposure to low (0.8 mg L-1 inorganic and 10 mg L-1 organic phosphate), medium (1.6 mg L-1 inorganic and 100 mg L-1 organic phosphate) or high (3.2 mg L-1 inorganic and 1000 mg L-1 organic phosphate) sublethal concentrations of these phosphates inhibit bactericidal clearance of the marine bacterium Vibrio sp. Bacteria were exposed to coelomic fluid collected from individuals maintained in either artificial seawater, or three concentrations of either inorganic phosphate or organic phosphate. Sterile marine broth, natural seawater and cell free coelomic fluid (cfCF) were employed as controls. Bacterial survival indices were measured at 0, 24 and 48 h periods once a week for four weeks. Bacteria were readily eliminated from the whole coelomic fluid (wCF) of individuals maintained in artificial seawater. Individuals maintained in inorganic phosphates were able to clear bacteria following a two week exposure period, while individuals maintained at even low concentrations of organic phosphates failed to clear all bacteria from their coelomic fluid. Exposure to phosphates represses antimicrobial defenses and may ultimately compromise survival of L. variegatus in the nearshore environment.

Hemodynamic effects of diuretic therapy in hypertension

The antihypertensive effect of diuretics is well documented. At least some preserved kidney function seems to be necessary to achieve a demonstrable effect. The importance of fluid volume reduction for the antihypertensive effect of these drugs during long-term treatment is however uncertain. The effects on central hemodynamics vary according to the literature, but the blood pressure reduction in responders (delta MAP greater than 10%) may primarily be explained by a reduction of the total peripheral vascular resistance. The peripheral circulation is influenced in the same way. Sometimes a flow reduction is observed, and sometimes a resistance reduction. In spite of a lasting blood pressure reduction after treatment with diuretics, the structural hypertensive vascular changes do not seem to be influenced.