Effects of ocean acidification on acid-base physiology, skeleton properties, and metal contamination in two echinoderms from vent sites in Deception Island, Antarctica

Antarctic surface waters are expected to be the first to experience severe ocean acidification (OA) with carbonate undersaturation and large decreases in pH forecasted before the end of this century. Due to the long stability in environmental conditions and the relatively low daily and seasonal variations to which they are exposed, Antarctic marine organisms, especially those with a supposedly poor machinery to eliminate CO₂ and protons and with a heavily calcified skeleton like echinoderms, are hypothesized as highly vulnerable to these environmental shifts. The opportunities offered by the natural pH gradient generated by vent activities in Deception Island caldera, Western Antarctic Peninsula, were used to investigate for the first time the acid-base physiologies, the impact of OA on the skeleton and the impact of pH on metal accumulation in the Antarctic sea star Odontaster validus and sea urchin Sterechinus neumayeri. The two species were sampled in four stations within the caldera, two at pH (total scale) 8.0-8.1 and two at reduced pH 7.8. Measured variables were pH, alkalinity, and dissolved inorganic carbon of the coelomic fluid; characteristic fracture force, stress and Young's modulus using Weibull statistics and Cd, Cu, Fe, Pb and Zn concentrations in the integument, gonads and digestive system. Recorded acid-base characteristics of both studied species fit in the general picture deduced from temperate and tropical sea stars and sea urchins but conditions and possibly confounding factors, principally food availability and quality, in the studied stations prevented definitive conclusions. Reduced seawater pH 7.8 and metals had almost no impact on the skeleton mechanical properties of the two investigated species despite very high Cd concentrations in O. validus integument. Reduced pH was correlated to increased contamination by most metals but this relation was weak. Translocation and caging experiments taking into account food parameters are proposed to better understand future processes linked to ocean acidification and metal contamination in Antarctic echinoderms.

Effects of field contamination by metals (Cd, Cu, Pb, Zn) on biometry and mechanics of echinoderm ossicles

Echinoderms are known to readily incorporate metals in their calcified endoskeleton. It is currently unclear if this has an impact on the skeleton function or if this can be considered as a detoxification mechanism. In the present work, populations of the sea urchin Echinus acutus and the starfish Asterias rubens were studied in stations distributed along a metal contamination gradient in a Norwegian fjord (Sørfjord). Ossicles involved in major mechanical functions - sea urchin spine and starfish ambulacral plate - were analyzed for their metal concentration (Cd, Cu, Pb and Zn) and their biometric and mechanical properties. Starfish plates were more contaminated by Cd, Pb and Zn than sea urchin spines. Cu concentrations were at background levels. In E. acutus, metals principally affected size. In A. rubens, material stiffness and toughness were decreased in the most contaminated station. This reduction is attributed either to the direct incorporation of metals in the calcite lattice and/or to deleterious effects of metals during skeleton ontogenesis. The contrasting incorporation of metals in the skeleton of the two investigated species accounts for the different impact of the metals, including in terms of fitness. The present results clearly indicate that, at least in A. rubens, incorporation of metals in the skeleton cannot be considered as a detoxification mechanism.

The “Micromorph” Cell: a New Way to High-Efficiency-Low-Temperature Crystalline Silicon Thin-Film Cell Manufacturing?

In the past, microcrystalline silicon (μc-Si:H) has been successfully used as active semiconductor in entirely μc-Si:H p-i-n solar cells and a new type of tandem solar cell, called the “micromorph” cell, was introduced [1]. Micromorph cells consist of an amorphous silicon top cell and a microcrystalline bottom cell. In the paper a micromorph cell with a stable efficiency of 10.7 % (confirmed by ISE Freiburg) is reported.

Among sofar existing crystalline silicon-based solar cell manufacturing techniques, the application of microcrystalline silicon is a new promising way towards implementing thin-film silicon solar cells with a low temperature deposition. Microcrystalline silicon can, indeed, be deposited at temperatures as low as 220°C; hence, the way is here open to use cheap substrates as, e.g. plastic or glass. In the present paper, the development of single and tandem cells containing microcrystalline silicon is reviewed. As stated in previous publications, microcrystalline silicon technique has at present a severe drawback that has yet to be overcome: Its deposition rate for solar-grade material is about 2Å/s; in a more recent case 4.3 Å/s [2] could be obtained. In the present paper, using suitable mixtures of silane, hydrogen and argon, deposition rates of 9.4 Å/s are presented. Thereby the dominating plasma mechanism and the basic properties of resulting layers are described in detail. A first entirely microcrystalline cell deposited at 8.7 Å/s has an efficiency of 3.15%.

N-I-P Micromorph Solar Cells on Aluminium Substrates

The first successful deposition of ‘micromorph’ silicon tandem solar cells of the n-i-p-n-i-p configuration is reported. In order to implement the ‘micromorph’ solar cell concept, four key elements had to be prepared: First, the deposition of mid-gap, intrinsic microcrystalline silicon (μc-Si:H) by the 'gas purifier method', second, the amorphous silicon (a-Si:H) n-i-p single junction solar cell, third, the microcrystalline silicon n-i-p single junction solar cell and fourth, the ability of depositing on aluminium sheet substrates.

All the solar cells presented have been deposited on flat aluminium sheets, using a single layer antireflection coating to couple the light into the cell. It is shown, that this antireflection concept- together with a flat substrate- holds for amorphous single junction solar cells, but it reaches its limit with the extended range of spectral response of the ‘micromorph’ cell.

The best initial efficiencies for each category of n-i-p cells on flat substrates were: 8.7% for the amorphous silicon single junction cell, 4.9% for the microcrystalline silicon single junction cell and 9.25% for the ‘micromorph’ tandem cell.

Microcrystalline Single-Junction and Micromorph Tandem Thin Film Silicon Solar Cells

Higher open circuit voltages of the microcrystalline silicon bottom cell have a direct impact on the efficiency of the micromorph (μc-Si:H/a-Si:H) tandem cell. In this paper it is shown that open circuit voltages over 500 mV can be achieved leading to gc-Si:H cell efficiencies of 8.5 %. The behaviour of such cells is characterised both by the illuminated and the dark I-V characteristics in function of cell temperature. Microcrystalline cells with Voc-values higher than 500 mV and micromorph tandems possess in general a lower value of the temperature coefficient of the fill factor and thus of the efficiency, when compared to c-Si. Temperature-dependent dark I-V measurements suggest that the dominant recombination mechanism in lgc-Si:H cells is different from that prevailing in a-Si:H solar cells.

Haemodilution induced by hydroxyethyl starches 130/0.4 is similar in septic and non-septic patients

BACKGROUND

Fluid therapy induces haemodilution related to plasma volume expansion. The aim of our study was to compare haemodilution after a single hydroxyethyl starches (HES) 130/0.4 infusion in two groups of patients, one with and one without sepsis. We hypothesized that a single HES challenge would induce similar sustained haemodilution in both groups.

METHODS

In this prospective preliminary study, patients predicted to require a single further volume-expander infusion were included immediately before receiving 500 ml of 6% HES 130/0.4 over a 15-min period. No additional fluid was administered over the next 8 h. Haematocrit, and serum albumin and protein were determined immediately before HES infusion then after 1, 2, 3, 4, and 8 h.

RESULTS

Twelve patients were included in each group. In both groups, all three haemodilution markers had significantly lower values after 1 h than at baseline. None of the values after 1 and 3 h differed significantly between the two groups. Neither did any of the other study variables show significant differences between the groups with and without sepsis.

CONCLUSION

We found that a starch-based compound was as effective in inducing haemodilution in patients with sepsis as in controls without sepsis, suggesting that HES may remain within the intravascular space even in patients with sepsis. Haemodilution parameters such as haematocrit, serum albumin and serum protein are useful for assessing the duration of plasma volume expansion induced by fluid therapy in critically ill patients.

Trace metal burdens and expression of heat stable low molecular mass proteins in the female asteroid Coscinasterias muricata--Fluctuations throughout the reproductive cycle

Concentrations of the essential trace metals copper and zinc were measured in the pyloric caeca of female Coscinasterias muricata sampled from Port Phillip Bay, Victoria, Australia at monthly intervals for 15 months. Results indicate that the concentrations of these metals appear to be regulated by the reproductive cycle. Peaks in zinc concentration occurred simultaneously with peaks in progesterone concentration in the pyloric caeca. These findings suggest that zinc plays a role in gametogenesis and ovarian development. Fluctuations in pyloric caeca copper concentration appear inversely related to the pyloric caecal index and associated with oocyte diameter, indicative of a role for this metal in oogenesis. The levels of cytosolic heat stable low molecular mass (LMM) proteins were examined throughout the sampling period. Heat stable LMM proteins (metallothionein-like) of 12 kDa and 7.5 kDa (apparent molecular mass) and the concentrations of copper appear to be related; although the exact nature of these proteins remains unknown. No such relationship was observed between the levels of heat stable LMM proteins and zinc.

Bioaccumulation and effects of PCBs and heavy metals in sea stars (Asterias rubens, L.) from the North Sea: a small scale perspective

Sea stars (Asterias rubens L.) were collected in different stations distributed in the Southern Bight of the North Sea. Concentrations of four heavy metals and six PCB congeners were measured in two body compartments (body wall and pyloric caeca). In order to assess the potential harm of these contaminants, two biochemical parameters were measured in sea stars, viz. reactive oxygen species (ROS) production by amoebocytes and cytochrome P450 immunopositive protein (CYP1A IPP) induction in pyloric caeca. Sea stars from stations located in the plume of the Scheldt river showed the highest contamination levels. Other stations, similarly located, displayed lower levels. No simple relationship could be established between ROS production by sea star amoebocytes and contaminant levels measured in sea star tissues. CYP1A IPP induction displayed more contrasted responses, and highly significant regressions were found between PCB concentrations measured in pyloric caeca and CYP1A IPP. Both biological parameters were found to vary significantly over the study area. On the whole, data indicated that contamination levels and subsequent effects in sea stars were comparable to those described in previous large-scale studies, but that working at a smaller scale highlighted the existence of patterns of contamination which can blur general trends due to major contamination sources like contaminated rivers.

Increased phagocytic activity in contaminated seastars (Asterias rubens) collected in the Southern Bight of the North Sea

In invertebrates, the phagocytosis exerted by immune cells constitutes the main line of internal defence against offending microorganisms. This study assessed during two consecutive years the phagocytic activity in seastars (Asterias rubens) collected in stations along the Belgian and Dutch coasts. The contamination of these seastars by metals and PCBs were measured in parallel. Increased phagocytic activities were found in seastars collected in the plume of the Scheldt river. This correlated with the contamination of seastars by metals, mainly Pb, but not with the contamination by the analysed PCB congeners. Furthermore, the relationship between phagocytosis and metal contamination was reproducible from one year to another. The possible mechanisms explaining this effect are discussed in light of a direct or indirect link between phagocytic activity and metal contamination of seastars.

Alteration of cellular immune responses in the seastar Asterias rubens following dietary exposure to cadmium

Several parameters of cellular immunity in seastars fed Cd-contaminated mussels were analyzed. The accumulation of cadmium in the seastars did not alter the concentration of amoebocytes in the coelomic fluid. On the contrary, the immune cells showed a reduced phagocytic activity and an increased production of reactive oxygen species. These effects may lead to an inability of the seastars to cope with bacterial infections and to oxidative damages to self tissue that could threaten the survival of the animals.

[Effect of August 2003 heat wave in France on a hospital biochemistry laboratory activity in Paris]

In August 2003, France sustained an exceptional heat wave. Heat-generated pathologies (dehydratation, heat stroke, cardio-vascular diseases) were responsible for additional biological analysis orders at the Saint-Antoine Hospital biochemistry laboratory in Paris from 4 to 18 august, compared to the same period in 2002. Variations were: + 17.6% for analysis orders, + 30.1% for ionograms, + 28.9% for plasma troponins I and + 58.6% for blood gazes analysis. Women and patients older than 75 years ratios were higher in august 2003. Biochemistry results analysis showed higher frequency of elevated plasma sodium, creatinine and troponin in 2003, confirming that most of patients admitted during heat wave were affected by heat-related diseases. Finally, laboratory excess activity was performed and quality was maintained, in spite of reduced staff and unusual climatic conditions.

Echinoderms as bioindicators, bioassays, and impact assessment tools of sediment-associated metals and PCBs in the North Sea

The study assessed the occurrence, possible toxicity, and impact of sediment-associated metals and PCBs in the coastal zone of the southern North Sea using echinoderms as representatives of the macrobenthos. Metals and PCBs were analyzed in the sediments and in the body compartments of the starfish Asterias rubens from 11 stations. The general toxicity of sediment-associated contaminants was assessed by bioassays using embryonic and larval developments of both A. rubens and the sea urchin Psammechinus miliaris. The impact of contamination was assessed by measuring cellular immune responses of A. rubens collected in the same stations. Contamination of the starfish by metals and PCBs closely reflected that of the sediments. However, bioaccumulation was element-specific for metals and depended on the chlorination pattern for PCBs. The sediment-associated contaminants appeared to be toxic in both the A. rubens and P. miliaris developmental assays. Moreover, metals were shown to affect the immune responses of starfishes living in contaminated stations. The most significant effects on biological responses were recorded in the plumes of the Scheldt/Rhine/North Sea Canal and the Elbe/Weser Rivers.

[Pulmonary migration of an axillary stent in a chronic hemodialysis patient]

The short-lived results of angioplasty for venous stenosis of a dialysis access led to stent placement. Its migration is a rare but dangerous complication, because of its final destination, that is right heart or pulmonary artery. We report on such a case and compare it with three cases found in literature.

Standardization of the lactulose-mannitol test in rats: application to burn injury

Intestinal permeability can be assessed by measuring urinary mannitol and lactulose excretion after oral administration. This test may be useful as a tool in experimental studies to explore the effects of specific diets intended to promote the repair of the integrity of the gut barrier. In this study we standardized the lactulose-mannitol test in rats and applied it to a burned-rat model. The conditions were: oral administration of an isotonic mixture of 50 mg of mannitol and 66 mg of lactulose, followed by aseptic collection of urine over 4 h. The increase in the lactulose/mannitol ratio in burned rats was due to higher lactulose excretion. These results corroborate those obtained in burn patients and show that our model is suitable for further experiments on nutritional manipulation.

Bacterial dissemination, rather than translocation, mediates hypermetabolic response in endotoxemic rats

OBJECTIVE

To study the pathogenesis of the host response during bacterial translocation, a rat model was designed for prolonged follow-up after injury.

DESIGN

A prospective, controlled animal study.

SETTING

Animal laboratory.

SUBJECTS

Young male Wistar rats.

INTERVENTIONS

Antibiotic decontamination of rats was performed 4 days before intragastric inoculation with a selected Escherichia coli strain (10(10) bacteria/kg of body weight). Two days later, the rats received a lipopolysaccharide injection or not (control group) and were observed for 3 days. They were then killed. A reference group (pair-fed healthy animals) was studied in parallel.

MEASUREMENTS AND MAIN RESULTS

During observations, urinary total nitrogen loss and 3-methylhistidine excretion were determined daily. When the rats were killed, mesenteric lymph nodes (MLNs), spleen, and liver were aseptically removed and cultured. Colonies identified as translocated E. coli were counted in each organ. Intracellular amino acid free pools were measured in extensor digitorum longus and anterior tibialis. Endotoxin induces bacterial translocation of bacteria from gut lumen to MLNs (100% vs. 59% in the lipopolysaccharide-untreated control group; p < .05) and dissemination to spleen and liver (65% and 45% of positive cultures after endotoxemia, respectively, vs. 6% and 12% in the control groups). No translocation occurred in the reference group. Evidence for the hypermetabolic response was seen in lipopolysaccharide-treated and infected rats, but protein catabolism was more closely related to the occurrence of bacterial dissemination to spleen and liver than to translocation alone (e.g., the cumulative 3-methylhistidine excretion during the observation period was 4.07+/-0.18 micromol in uninfected rats, 4.48+/-0.29 in rats with positive MLN cultures alone and 6.17+/-0.30 in MLN, spleen, or liver infected rats; 1 vs. 2, NS; 3 vs. 1, and 3 vs. 2, p < .05).

CONCLUSIONS

Gut barrier failure is associated with a deep excessive catabolic response in the host. The mechanism by which the metabolic state affects the resistance to infection apparently involves amino acid metabolism.

Intestinal permeability in liver cirrhosis: relationship with severe septic complications

OBJECTIVES

Patients with liver cirrhosis are at high risk of severe septic complications such as spontaneous bacterial peritonitis (SBP) and bacteraemia. The aims of this study were to assess intestinal permeability in patients with liver cirrhosis and to search for a relationship between an impaired intestinal permeability and the occurrence of severe septic complications.

METHODS

Intestinal permeability was assessed in a group of 80 cirrhotic patients (Child A, n = 13; Child B, n = 26; Child C, n = 41) and 28 healthy control subjects. A severe septic complication (bacteraemia and/or SBP) occurred in 16 patients, within 10 days before (n = 8 cases) or after (n = 8 cases) the test was performed. Lactulose (LAC) 10 g was given orally together with mannitol (MAN) 5 g, and urinary excretion rates were determined.

RESULTS

Urinary mannitol excretion (MAN%) was lower while the LAC/MAN ratio was higher in patients than in control subjects (P < 0.001); these abnormalities were more marked in Child C patients (Child C patients vs control subjects: MAN%, 8.20 +/- 0.79 vs 14.59 +/- 0.58, P < 0.001; LAC/MAN, 0.066 +/- 0.026 vs 0.017 +/- 0.001, P < 0.02). When compared with non-infected patients, septic patients had a lower MAN% and an increased LAC/ MAN ratio (5.45 +/- 1.12 vs 9.83 +/- 0.87, P < 0.02; 0.130 +/- 0.063 vs 0.029 +/- 0.005, P < 0.02).

CONCLUSION

Although the main mechanism involved in the decrease in MAN% is likely a reduction in area of the intestinal absorptive surface, these results argue in favour of an increased intestinal permeability in liver cirrhosis, especially in patients with severe infectious complications. The impairment of intestinal function barrier may contribute to severe septic complications in these patients.

Severe dietary restriction initiated in aged rats: evidence for poor adaptation in terms of protein metabolism and intestinal functions

BACKGROUND

Protein energy malnutrition is a common finding in elderly people, increasing morbidity and mortality in aged inpatients. Investigations need to be developed to counteract malnutrition-induced alterations early and to avoid potential irreversible lesions. The aim of this experimental study was to evaluate time-response to severe dietary restriction (DR) initiated in aged rats in terms of protein metabolism and digestive trophicity.

MATERIALS AND METHODS

After the acclimatization period, 22-month-old male rats were randomized into six groups: three control groups, fed ad libitum for 3, 6 or 12 weeks with a standard diet and three corresponding dietary-restricted groups fed for the same periods with only 50% of the spontaneous intake. Intestinal mucosa, liver and skeletal muscles (soleus, extensor digitorum longus and tibialis anterior muscle) were removed when the rats were killed.

RESULTS

DR induced dramatic body weight loss (up to 50% of initial body weight after 12 weeks DR). Protein metabolism was affected in terms of nitrogen balance (P < 0.01) and protein content, in particular at the splanchnic level. Morphometrically, the intestine structure was altered after 12 weeks of DR (P < 0.01), and this atrophy was correlated with malabsorption of mannitol (P < 0. 01). Ileal hydrolase activities were decreased throughout the 12 weeks of DR.

CONCLUSIONS

Aged rats clearly exhibit a defect of adaptation to long-term DR initiated at an advanced age. Severe DR leads to malnutrition, which becomes of major importance after 12 weeks, in particular at the intestine level. Hence, application of these experimental results to elderly, malnourished people may contribute to a better knowledge of denutrition-induced disorders.

Is the L-arginine-nitric oxide pathway involved in endotoxemia-induced muscular hypercatabolism in rats?

We investigated the role of the nitric oxide (NO) synthase (NOS) pathway in muscular metabolism during endotoxemia in four groups of male Wistar rats. Two groups were injected with the lipopolysaccharide (LPS) of Escherichia coli (3 mg/kg), with one group treated using N(G)-nitro-L-arginine methylester ([L-NAME] 85 mg/kg/d) and the other not. The two control groups included one treated with L-NAME and the other not. After 24 hours of fasting, the rats were fed by controlled enteral nutrition and killed on day 3. The results showed that (1) NOS inhibition was detrimental during endotoxemia, increasing lethality from 20% to 80.5%, and (2) NOS inhibition did not modify the hypercatabolic state consecutive to endotoxemia, particularly at the muscular level (nitrogen balance, total-body and muscular weight loss, and muscular protein and glutamine concentrations). However, myofibrillar catabolism was delayed in the LPS-NAME group. In conclusion, NO production is of major importance for survival after an endotoxemic challenge, but contributes weakly to the metabolic response of muscle to injury.

Intestinal absorption and permeability in human immunodeficiency virus-infected patients

BACKGROUND

Impaired intestinal function could account for diarrhoea and weight loss, which are common features of advanced human immunodeficiency virus (HIV) infection.

METHODS

We assessed intestinal permeability to lactulose and mannitol and absorption of D-xylose in 96 HIV-infected patients (group I: asymptomatic subjects (CDC-A); group II: symptomatic subjects (CDC-B or C) without body weight loss and/or diarrhoea; group III: 25 acquired immunodeficiency syndrome (AIDS) patients (CDC-C) with severe body weight loss and/or diarrhoea) and 10 healthy subjects as controls.

RESULTS

An incremental decrease in urinary D-xylose recoveries was observed, with all groups statistically different from each other. Impaired intestinal permeability was only found in patients of group III (statistically different from all other groups).

CONCLUSIONS

These findings suggest a loss of intestinal functional absorptive surface as HIV disease progresses. This process may be present at the early stage of infection. Impaired intestinal permeability is observed later in AIDS patients when digestive signs are present, particularly diarrhoea.

Glucose does not facilitate the absorption of sorbitol perfused in situ in the human small intestine

Sorbitol is better absorbed in the small intestine when ingested concomitantly with glucose. The aim of this study was to test in situ the effect of glucose on the absorption of sorbitol in the human small intestine, using the perfusion technique. The sorbitol absorption of three test solutions, perfused in a random order, was measured in a 30-cm segment of jejunum in six healthy volunteers (4 males and 2 females). The solutions contained the same concentration of sorbitol (55 mmol/L) and increasing concentrations of D-glucose (0, 55 and 110 mmol/L). Net absorption of water increased as the glucose concentration of the solution increased and differed significantly among the three solutions. Net absorption of glucose was significantly greater for the 110 mmol/L glucose solution than for the 55 mmol/L glucose solution [23.6 +/- 1.8 vs. 11.0 +/- 1.2 mmol/(h x 30 cm), P < 0.01]. Sorbitol absorption in the jejunal segment was 5.2 +/- 1.3, 6.2 +/- 0.5 and 5.8 +/- 0.4 mmol/(h x 30 cm) for the glucose-free solution, the 55 mmol/L glucose solution, and the 110 mmol/L glucose solution, respectively. These values did not differ significantly. These results do not support the hypothesis of a facilitating effect of glucose on sorbitol absorption in the human small intestine.

Kinetic nephelometric determination of albumin produced by rat hepatocytes in culture

A kinetic immunonephelometric method for the determination of albumin produced by rat hepatocytes in culture is described. This assay is simple, rapid and sensitive. The methodology allows detection of 0.7 mg/l albumin in 200 microliters of culture medium. Within-run precision CVs for three levels of concentrations were under 1.0% and between-day precision CVs were under 4.1%. The range of measurement obtained using appropriately diluted samples was 1.2 to 74 mg/l. The rabbit IgG fraction to rat albumin used in this method did not cross-react with albumin from cow, allowing the use of fetal calf serum in the medium. The method described can thus be used easily for the assessment of albumin synthesis in cellular studies using isolated hepatocytes.

No evidence for a tumor necrosis factor alpha stimulated 2-methylaminoisobutyric acid uptake in hepatocyte monolayer

This study investigates the short-term effects of glucagon and human recombinant tumor necrosis factor alpha (TNF alpha) singly and in association on 2-methylaminoisobutyric acid (MeAIB) transport in hepatocyte monolayers. As expected, glucagon induced a time-dependent stimulation of MeAIB transport. In our experimental conditions, TNF alpha did not induce cytolysis. A 2 hour exposure to TNF alpha (0.05-500 ng/l) with or without glucagon (10(-9) to 10(-6) M) did not modify the basal or glucagon-stimulated MeAIB transport. Varying the duration of exposure to TNF alpha 5 ng/l up to 6 h was equally ineffective. The presence of hydrocortisone potentiated the glucagon-stimulated transport, but TNF alpha remained ineffective. Finally, the association of interferon (IFN gamma) with TNF alpha and/or glucagon was unable to modify the transport activity. These data demonstrate that TNF alpha does not exert a direct effect on MeAIB transport in hepatocytes, at least on a short-term basis.

Gas chromatography applied to the lactulose-mannitol intestinal permeability test

Intestinal permeability can be modified by various illnesses, trauma and sepsis. Alterations of the intestinal wall can facilitate the diffusion of potentially harmful substances such as endotoxins, as well as bacterial translocation. We describe the validation of a capillary gas chromatographic method for the determination of mannitol and lactulose, used as intestinal permeability probes. The method is linear up to 3 g/l for mannitol and 300 mg/l for lactulose; recovery from overload samples is between 92 to 110%. Intra-assay coefficients of variation (C.V.s) were 2.7 and 6.8% for mannitol and lactulose, respectively, and inter-assay C.V.s were 8.9 and 9.3%. Normal values for 25 healthy subjects (mean +/- S.D.) were 14.5 +/- 3.1% and 0.27 +/- 0.15% for mannitol and lactulose, respectively. The GC method presented is rapid and precise.

[Cor triatriatum of adults. Apropos of 2 new surgically treated cases in adults]

The authors report two cases of cor triatriatum in a 54 year old woman undergoing open heart surgery with a preoperative diagnosis of mitral stenosis, and a 24 year old woman in whom the diagnosis had been made before surgery. Resection of the abnormal intra-left atrial fibrous membrane successfully restored normal haemodynamics in both cases. The main clinical and diagnostic features of the condition are described.

[Subclavian floating thrombus responsible for encephalo-digital syndrome. 2 cases]

Two patients developed acute, evolutive ulcerations of the fingers simultaneously with acute, transient insufficiency of the vertebral and basilar arteries. Emergency angiography or the aortic arch showed no obvious lesion, but in both cases selective exploration of the subclavian vessels demonstrated the presence of a small floating thrombus giving rise to a "shower" of emboli. The diagnosis was confirmed and the thrombi excised by surgery through the subclavian route. Multiple emboli in different territories are usually due to heart diseases. Our cases suggest that the possibility of a subclavian thrombus should be borne in mind and that in patients with normal hearts the supra-aortic vessels should be adequately explored by angiography.

[Long-term course of patients with Smeloff-Cutter aortic valve prosthesis]

The long-term results (5 to 12 years) of 77 patients with Smeloff-Cutter aortic valve prostheses are reported. These patients were comparable in age, preoperative clinical condition and type of aortic valve replacement. The postoperative follow-up period of this series was however significantly longer. The 5 year survival rate was of 87%. The causes of death included thromboembolism, infectious endocarditis and cardiac failure. Mortality was higher in the first 5 postoperative years : 2,4% patient-years compared to 1,5% patient-years in the following years. Thromboembolism and neurological complications were particularly rare, representing a risk of 1,04% patient-years but these complications were lethal in half the cases in which they occurred. No haemolytic complications were observed. Infective endocarditis always occurred in patients with a history of infection, the complication usually being late (after 3 years). The life expectancy of patients seen after 5 years is at least 5 additional years in 80% of cases. The haemodynamic profile of the prosthesis did not degrade with time. After 5 years, 58,6% of patients in functional Class IV at operation were in Class I or II afterwards. 84,4% of patients operated in functional Class III were in Class I or II, and 93% operated in functional Class II were in Class I or III. A control of 3 prostheses carried out by the Cutter laboratory after 10 and 11 years' function shows practically no deterioration of the prosthesis. The low incidence of thromboembolism, the absence of haemolysis and long-term deterioration of the prosthesis are particularly valuable characteristics of this prosthesis in the aortic position.