Evaluating the long-term performance of low-cost adsorbents using small-scale adsorption column experiments.

This study investigated a novel method of predicting the long-term phosphorus removal performance of large-scale adsorption filters, using data derived from short-term, small-scale column experiments. The filter media investigated were low-cost adsorbents such as aluminum sulfate drinking water treatment residual, ferric sulfate drinking water treatment residual, and fine and coarse crushed concretes. Small-bore adsorption columns were loaded with synthetic wastewater, and treated column effluent volume was plotted against the mass of phosphorus adsorbed per unit mass of filter media. It was observed that the curve described by the data strongly resembled that of a standard adsorption isotherm created from batch adsorption data. Consequently, it was hypothesized that an equation following the form of the Freundlich isotherm would describe the relationship between filter loading and media saturation. Moreover, the relationship between filter loading and effluent concentration could also be derived from this equation. The proposed model was demonstrated to accurately predict the performance of large-scale adsorption filters over a period of up to three months with a very high degree of accuracy. Furthermore, the coefficients necessary to produce said model could be determined from just 24 h of small-scale experimental data.

The pathway to drive decompression microbubbles from the tissues to the blood and the lymphatic system as a part of this transfer.

The formation sites of the microbubbles that are routinely detected in the bloodstream at precordial level by Doppler after a decompression are reviewed and discussed here. First, microbubbles could form on the endothelium lumen wall of the capillaries, at specific nanometric sites, but the release mechanism of such small emerging entities remains puzzling. They could be also formed from pre-existing gas nuclei present in the blood when favorable local hydrodynamic/supersaturation conditions generate microcavitation and tribonucleation phenomena. Finally, tissues could represent large pools for microbubble formation and amplification. Nevertheless, it remains to explain what the potential pathways are to drive them to the blood. Knowing that the permeability of most of the blood capillary network is quite low, an alternative is proposed for such transport. The lymphatic system, which drains the interstitial fluid to guarantee the fluid balance of tissues, could allow the transfer of micrometric elements like stabilized microbubbles formed in tissues on long distances. A final rejection in the bloodstream at the termination of both right lymphatic and thoracic ducts can be expected. The characteristics of this slow transport, activated by the muscular pump, could explain the detection on long periods of massive venous gas emboli.

Pulmonary function in men after repeated sessions of oxygen breathing at 0.25 MPa for 90 min.

HYPOTHESIS: We wanted to evaluate the pulmonary effects of discontinuous oxygen breathing (15 min O2, 2 min air breaks, 15:2), at 0.25 MPa once a day for 90 min O2 (6 sequences) over 10 d. This sequence, which has never been evaluated, is currently used in our hyperbaric therapy center. METHODS: Clinical and functional pulmonary status (questionnaire, spirometry, flow/volume loop, pulmonary diffusing capacity for carbon monoxide) was assessed in 10 non-smoking healthy volunteers after one exposure at 0.25 MPa consisting of 90 min of discontinuous oxygen breathing (15:2) and in 10 non-smoking patients who received a hyperbaric treatment consisting of 90 min of the same discontinuous O2 breathing (15:2) once a day over 10 d. The patients received daily intravenous methylprednisolone (1 mg x kg(-1)) and nicergoline (60 mg). RESULTS: There were no respiratory symptoms in either group. As expected, for a single exposure of that duration, lung function did not change in volunteers; however, a significant decrease in maximal expiratory flows (MEF) at 50 (-15%) and 25% (-33%) of forced vital capacity (p < 0.05) without change in forced vital capacity (FVC) appeared in patients treated over 10 d. CONCLUSION: Repetition of the 15:2 oxygen breathing sequence for 90 min once a day over 10 d led to greater flow limitation in peripheral airways than reported after continuous oxygen breathing of 210 min at 0.3 MPa which showed a 7% decrement in MEF50 and a 12% decrement in MEF25. No studies reporting these indexes were found in the 0.2-0.25 MPa range. Similar decrements in MEF50 and MEF25 with steady FVC have been reported after 14 d of daily hyperbaric therapy (0.24 MPa) with 30:5 sequence (-9% and -13%, respectively), 80% of the patients were symptom free. Similarily, our patients were all symptom free and remained so 1 yr after the study, hence, this toxicity is of weak clinical significance in subjects free of inflammatory lung diseases. HBO therapy, though safe, is not totally without effect on the lung.

[The biological characterization of HIV-1 isolated in patients with a rapid clinical evolution]. / Caracterización biológica de aislamientos de VIH-1 en pacientes con una evolución clínica rápida.

The biological characteristics of 11 HIV-1 strains isolated from patients with a fast clinical evolution to AIDS were studied. The viral isolates were classified according to their replication kinetics and cell tropism. Taking into account these criteria, it was observed that 8 of the isolated strains (72.7%) were of rapid high growth (RH) or slow low 3 (SL3) with preferential tropism to the lymphocytic stock, as it corresponds to AIDS patients. 3 (27.3%) had characteristics of slow low 1 (SL1). The cytopathogenicity of the strains was studied in the MT4 cellular line, and it was observed that most of them (72.7%) were syncytium-inducing strains (SI), which allowed to prove the in vivo and in vitro relation of the biological properties. It was not so in 3 of the cultures (27.3%) that behaved as non-syncytium inducers.

A longitudinal study of lung impairment in patients with primary Sjögren's syndrome.

OBJECTIVE: A longitudinal evaluation of lung involvement in primary Sjögren's syndrome (SS). METHODS: Eighteen non-smoking women fulfilling the European criteria for primary SS were followed for 55 months (range 26-137 mos.). These were consecutive patients with exclusion for current smokers and patients with lung diseases. Every patient underwent clinical examination, chest radiographs and lung function tests (spirography, flow/volume loop and CO lung diffusing capacity measurements). No patient was given any immunosuppressive or mucolytic therapy. RESULTS: Cough, dyspnea on exertion and recurrent bronchitis were observed in 50, 40 and 20% of the patients respectively and their frequency did not change with time. Chest radiographs were and remained normal. At presentation, lung volumes and diffusing capacity were in the normal range, whereas expiratory flows in the small airways tended to be in the low range. With time, the peak expiratory flow (PEF) significantly increased (95.8 +/- 4.6 v 103.5 +/- 4.6, mean +/- SE, % of predicted, Wilcoxon, p < 0.05) whereas the lung transfer factor for CO (TLCO) and the transfer coefficient (KCO = TLCO/alveolar volume) decreased (92.9 +/- 4.0 v 87.0 +/- 4.0 and 89.7 +/- 2.4 v 84.2 +/- 2.6 respectively, p < 0.05 for both). The TLCO decrease, corrected for the duration of follow-up, correlated with the titers of IgA circulating immune complexes (CIC) at presentation and to a lesser extent with the occurrence of cough. CONCLUSION: During the follow-up of these primary SS patients, respiratory symptoms did not change, the recurrent respiratory infection rate was low, and no cases of pulmonary hypertension or lymphoma was observed. The diffusion capacity decrease was associated with IgA CIC titers at presentation. This impairment could contribute to dyspnea during its evolution over a lifetime but is too slight to explain the dyspnea on exertion seen in most of our patients.

gamma-Aminobutyric acid concentrations in the cerebrospinal fluid of newborn infants determined by high performance liquid chromatography.

gamma-Aminobutyric acid (GABA), a major inhibitory amino acid, has a central role in cardiorespiratory regulation. Its measurement in the cerebrospinal fluid (CSF) complements the study of neurotransmission systems. Forty-one children were studied (postnatal age < 1 year). For each child, date of birth, date of sampling and current treatments were collated and their postnatal (days) and postconception (weeks) ages were calculated. CSF samples were studied using reverse phase high performance liquid chromatography (HPLC) with o-phthaldialdehyde derivation and spectro-fluorimetric measurement. A clear increase in levels of GABA was observed around 41 weeks postconception, followed by a progressive decrease, with levels stabilizing after 57 weeks postconception. GABA-regulated neuromodulation therefore appears to be mature at 41 weeks postconception and not at birth. The data could be used in further studies investigating amino acid metabolism in relation to brain function in various neurological disorders.

Effects of a temperature increase on oxygen consumption of yellow freshwater eels exposed to high hydrostatic pressure.

Oxygen consumption was measured in yellow freshwater eels, Anguilla anguilla, during exposure to a hydrostatic pressure (HP) of 101 atmosphere absolute (ATA) for 3 h, either with or without a 5 degrees C increase in water temperature. It was found that concomitant increases in temperature and pressure resulted in an increase in oxygen consumption that was lower than when pressure alone was increased. When eels were acclimated to HP for 21 days and then submitted to a temperature increase of 5 degrees C, this induced a significant increase in oxygen consumption but only during the first hour. It is therefore concluded that raising the water temperature during the first hours under pressure could counterbalance the pressure effects on membrane fluidity in a thermodynamic manner and thus help shallow-water fish acclimate to high pressure. In contrast, when acclimation processes are ended, the temperature effect disappears within 1 h.

[Effects of hydrostatic pressure on malondialdehyde (MDA) determination in brain from yellow freshwater eels]. / Effets de la pression hydrostatique sur les concentrations de malondialdéhyde (MDA) dans l'encéphale d'anguilles de livrée jaune.

Malondialdehyde (MDA) content in a tissue can be an indicator of lipoperoxidation and thus of membrane alteration. MDA concentrations have been measured in the brain of yellow freshwater eels (Anguilla anguilla) submitted to 1.51 or 101 ATA of hydrostatic pressure. Exposure to pressure was performed for 6 h at constant water temperature and in normoxic conditions. The results thus obtained show a significant increase (P < 0.05 or better) of MDA brain concentrations at 51 ATA (+ 124%) and 101 ATA (+ 290%). These results mean that hydrostatic pressure is able to activate lipoperoxidation and can alter membrane functions together with the decrease in membrane fluidity it induces. Such a membrane alteration can explain, at least in part, the excitation periods which are observed during and after animal compression.

Amino acids and ammonia in the cerebral cortex, the corpus striatum and the brain stem of the mouse prior to the onset and after a seizure induced by hyperbaric oxygen.

The contents of amino acids (AA) and ammonia (NH3) were measured in corpus striatum, brain stem and cerebral cortex of two strains of mice exposed to hyperbaric oxygen (HBO). Mice of the HBO-sensitive strain (CD1) were exposed to 600 kPa O2 for 24 min versus 90 min for mice of the normal C57 strain, so that 50% of the mice in both strains developed a generalized convulsion. In the cortex of exposed but unconvulsed (EXUN) C57 mice, the contents of taurine, glutamine and NH3 increased while that of GABA decreased when compared to control mice. In the CD1 mice, NH3 content was increased while that of Asp decreased. After a convulsion, NH3 was increased in both strains, the AA contents returned to normal in C57 but Asp remained low in CD1 mice. Somewhat similar changes occurred in the striatum except that NH3 levels were less affected while GABA ones were significantly decreased in the CD1 mice exposed to HBO, whether convulsed or not. In the EXUN brain stem, Asp and Glu contents decreased. These decreases were greater in C57 on a percentage basis than in CD1 mice. GABA content was decreased in the C57 strain. After a convulsion, Asp and Glu levels remained low and NH3 accumulated in CD1 whereas in C57 only the Glu level was decreased. The cortical and striatal changes may indicate a lesser GABA supply in C57 strain and some Asp release in CD1 strain. In the brain stem of both strains, Asp and Glu release is possible in addition to GABA in C57 strain.(ABSTRACT TRUNCATED AT 250 WORDS)

[Normal values of respiratory function tests. Safety of normalized regression equations]. / Normalité des explorations fonctionnelles respiratoires. Sécurité des équations de régression "normatrices".

A frequent question in lung function testing is the extent of the margin of error in the measurements. Is the confidence interval (CI) of the usual summary equations for reference values larger than the sum of every possible error including interindividual variations and measurement errors which come from the apparatus, the technician and the patient? The analysis of the data of several authors including our data (lung function laboratory of Brest University hospital) leads to the conclusion that the summary equations of Quanjer et al. (1993) may be used safety as the CI is larger than the sum of all errors. However, this is only true if lung function testing is performed in optimal conditions, i.e. with frequently checked and carefully calibrated apparatus used by professional technicians in cooperating patients.

[Characteristic aspects of vascular complications in renal transplantation in children]. / Aspects particuliers des complications vasculaires dans la transplantation rénale de l'enfant.

In a series of 859 transplantations performed in children and adolescents from January 1973 to December 1992, vascular thrombosis accounted for 18% of all graft losses (2nd cause of graft failure), and 57% of early failures (within 2 months). Renal veins and arteries were equally affected. The young age of the donors and recipients constituted the main risk factor, thrombosis accounting for 40 and 37% respectively of all graft losses in donors and recipients < 5 years old. This explained the lower survival rate of these age groups after grafting, as reported in most published pediatric series. The prophylactic use of a low molecular weight heparin in high-risk grafts may help to decrease its incidence. A renal artery stenosis, located a few cm beyond the anastomosis in 2/3 of cases, was observed in 10% of grafts. Often severe hypertension (HBP) with cerebral complications, responsible for permanent sequelae in some cases, was the prominent symptom. Anti-hypertensive drug therapy was sufficient to control HBP in 40 cases out of 72, and in 10 of these, a spontaneous regression of the stenosis was remarked within a few months after repeated angiography. Transluminal angioplasty was used on 26 stenosis and was effective in 2/3 of cases; the recurrence rate, however, was 27%.

Effect of hyperbaric oxygen on prostaglandin and thromboxane synthesis in the cortex and the striatum of rat brain.

The effect of a previous exposure to hyperbaric oxygen (HBO) on the synthesis capacity of prostaglandin (PG) and thromboxane (TX) was investigated in the brain of male rats. Three groups of rats were used: 1. Neurotoxic HBO (n = 11): The rats were exposed to sixfold the atmospheric pressure (101.3 kPa), i.e., 6 absolute atmospheres (ATA), of pure O2 up to the first convulsion (6 ATA O2); 2. Mild hyperoxia (n = 10): The rats were exposed to compressed air at the same absolute pressure and for a similar time than that of the neurotoxic HBO group (here PO2 is 1.26 ATA); 3. Normoxia at atmospheric pressure (PO2 is 0.21 ATA) for control. There was no convulsion in groups 2 and 3. Decompression of the high pressure groups lasted 15 min. After decapitation, samples of the frontal cortex and the striatum were taken, weighed, washed, and then incubated in Krebs-Ringer bicarbonate for 1 h. The release of eicosanoids in the medium was determined by enzyme immunoassay. Mild hyperoxia only significantly reduced in the striatum the release of 6-keto-PGF1 alpha (1.3 +/- 2.4 vs 10.9 +/- 6.6 pg/mg wet tissue, p < 0.001; mean +/- SD) and PGE2 (3.2 +/- 2.7 vs 7.8 +/- 6.5 pg/mg wet tissue, p < 0.05), whereas TXB2 did not change.(ABSTRACT TRUNCATED AT 250 WORDS)

[Activity of plasma dopamine-beta-hydroxylase in newborn infants. Implication in prematurity, maternal pathology and growth]. / Activité dopamine-beta-hydroxylase plasmatique chez le nouveau-né. Implication de la prématurité, de la pathologie maternelle et de la croissance.

The aim of the study was to determine plasma dopamine-beta-hydroxylase activity (DBH) in newborn infants and possible changes with maturation, mode of delivery and maternal disease: pregnancy-induced hypertension and gestational diabetes. DBH activity was determined by high performance liquid chromatography from 82 neonates divided in 2 groups: group I: 27 neonates (age: 1 to 8 days) including 6 preterm and 21 full-term neonates; group II: 55 full-term neonates divided in 5 classes: A: vaginal delivery; B: forceps; C: elective caesarean section; D: vaginal delivery and maternal hypertension; E: vaginal delivery and gestational diabetes. The plasma DBH activity was low in neonates and not influenced by prematurity. Significantly lower DBH activity was found after caesarean section. Hypertension and gestational diabetes did not affect umbilical cord plasma DBH activity.

Effect of one hyperbaric oxygen-induced convulsion on cortical polyamine content in two strains of mice.

In rat striatum, after one hyperbaric oxygen (HBO)-induced convulsion, polyamine changes are found that could promote N-methyl-D-aspartate (NMDA) activation. In the HBO-sensitive CD1 mouse, unlike in the common C57 strain, there is some support for NMDA activation after the HBO seizure. We measured PA cortical content before and after the first HBO-induced convulsion (about 608 kPa O2) in CD1 and C57 strains. Putrescine, spermidine and spermine were dansyl derived and analysed by HPLC. Exposure to HBO significantly increased putrescine content only in CD1 though a similar trend was observed in C57. No further increase was observed after convulsion whatever the strain. There were no significant changes in spermidine or spermine to support NMDA activation. Therefore, putrescine increase in CD1 cortex could reflect the free radical formation that is known to be greater in CD1 than in C57 mouse. Attempts to increase putrescine levels before HBO exposure hastened HBO-induced convulsion, less than spermidine or spermine. Because of physiological polyamine interconversion, additional experiments with indirect manipulation of putrescine levels and study of their time-course would precise these preliminary reports on putrescine and HBO.

[Medical value of a respiratory mixture of oxygen and helium (Heliox)]. / Intérêt médical des mélanges respiratoires oxygène-Hélium (Héliox).

Lighter and more viscous than air, the oxygen-helium mixtures (heliox), well known to respiration physiologists, are used for functional exploration in the diagnosis of airways obstructions; they are also administered to deep-sea divers. However, it is usually little known that heliox can be used as therapeutic agent in the treatment of acute respiratory distress or severe disorders of ventilation caused by obstruction (e.g. inflammation). Heliox reduces the ventilatory work and increases alveolar ventilation, thereby improving haematosis and carbon dioxide elimination. The English-speaking authors, in particular, have a large experience of oxygen-helium mixtures in the treatment of such pathologies as severe asthma, small airways obstruction, cystic fibrosis, bronchoalveolitis, post-extubation pathologies, pharyngo-laryngeal oedema and drowning. The oxygen-helium mixture, therefore, participates efficiently, simply and inaggressively in the treatment of airway obstruction and acute respiratory distress.

Changes in striatal and cortical amino acid and ammonia levels of rat brain after one hyperbaric oxygen-induced seizure.

Changes in amino acids (AA) and ammonia were investigated in the cerebral cortex and striatum of rats after the following conditions: 1) one hyperbaric oxygen (HBO)-induced seizure (6 ATA O2); 2) exposure to 6 ATA air; and 3) exposure to atmospheric pressure (no seizures in both latter groups). Exposure to 6 ATA air produced no change with respect to atmospheric pressure. After HBO seizure, AA levels (except for gamma-amino butyric acid, GABA, and glutamine), with respect to 6 ATA air levels, were altered in the striatum with a concomitant rise in ammonia (+70%) at variance with the cortex. These changes could be explained by increased oxidative deamination in the striatum. Decrease in taurine content (-66%) in the striatum, where HBO lipoperoxidation exists, suggests an alteration of glial function leading to blockade of uptake and loss of released products in interstitial fluid. This pattern of change recalls the one seen in ischemic conditions, but cannot be confirmed in the absence of measurements of extracellular amino acid levels under HBO conditions. The maintenance in the level of GABA would favor its role in controlling seizure. In the cortex, only a few AA levels decreased, along with a nonsignificant trend for ammonia to increase. The remaining abnormalities in the striatum, after the first HBO seizure, may explain the already known repetition of seizures in continuously exposed animals and are consistent with previous data on the important role of the striatum.

[External resistances and dyspnea. Value of the study of flow-volume loops]. / Résistances externes et dyspnée. Intérêt de l'étude de la boucle débits/volumes.

Breathlessness induced by external resistances (diaphragms with orifice size of 20, 15, 10, 7.5 and 5 mm) introduced in the ventilatory circuit of a spirometer and the corresponding parameters of a maximal flow-volume loop have been studied. 10 healthy subjects (5 men, 5 women), free from any acute or chronic cardiorespiratory disease, volunteered for this study. The results showed that the breathlessness (severe or moderate) was especially correlated with the decrease in peak flows, peak inspiratory flow (PIF) more than peak expiratory flow (PEF): when breathlessness was moderate, PIF was more decreased than PEF, -35% and -28% respectively; when breathlessness became severe, PIF also decreased more than PEF, -60% and -50% respectively; forced vital capacity (FVC) never changed and maximal expiratory flows at 50% and 25% of FVC were only slightly modified despite obvious breathlessness. The increase in diaphragmatic activity seemed more implicated than the activation of expiratory muscles in the genesis of breathlessness. PIF more than the commoner PEF could be a useful marker of the breathlessness perceived by the patient during acute bronchial obstruction (asthma).

[Neurotransmission and sudden infant death. Study of cerebrospinal fluid]. / Neurotransmission et mort subite du nourrisson. Etude du liquide céphalo-rachidien.

The study of 33 cerebrospinal fluids of infants victims of sudden death shows a very significant increase of the metabolites of dopamine and serotonin. These determinations, compared to a control group, indicate a failure, concerning these two neurotransmitters, which could induce a cardiorespiratory seizure. This failure has likely a multifactorial origin.