Immobilization of Enzymes into a Polyionic Hydrogel: ChitoXan

Three enzymes were immobilized onto polyionic hydrogel, ChitoXan, obtained by complexation between chitosan and xanthan. The biocatalysts used were two proteases (protease type XIX from Fungal d’Aspergillus sojae and the trypsin type II.S from Porcine Pancreas) and a lipase (lipase Type VII from Candida rugosa). The immobilization efficiencies and the relative activities were investigated for these enzymes. The immobilization efficiencies changed with each enzyme and varied between 53 and 80%. Good relative activities were found for the lipase Type VII from Candida rugosa and the protease type XIX from Fungal d’Aspergillus sojae. For the latter, the influence of several factors were studied: molarity of the storage buffer, storage temperature and time of hydrogel, and the enzyme concentration. For the immobilized lipase, hydrolysis of olive oil in aqueous and organic media has been compared. This study confirmed that the lipase modified the external and internal structure of the hydrogel from fibrillar to the formation of globular structures in the presence of lipases.

Dual stimuli-responsive coating designed through layer-by-layer assembly of PAA-b-PNIPAM block copolymers for the control of protein adsorption

In this paper, we describe the successful construction, characteristics and interaction with proteins of stimuli-responsive thin nanostructured films prepared by layer-by-layer (LbL) sequential assembly of PNIPAM-containing polyelectrolytes and PAH. PAA-b-PNIPAM block copolymers were synthesized in order to benefit from (i) the ionizable properties of PAA, to be involved in the LbL assembly, and (ii) the sensitivity of PNIPAM to temperature stimulus. The impact of parameters related to the structure and size of the macromolecules (their molecular weight and the relative degree of polymerization of PAA and PNIPAM), and the interaction with proteins under physico-chemical stimuli, such as pH and temperature, are carefully investigated. The incorporation of PAA-b-PNIPAM into multilayered films is shown to be successful whatever the block copolymer used, resulting in slightly thicker films than the corresponding (PAA/PAH)n film. Importantly, the protein adsorption studies demonstrate that it is possible to alter the adsorption behavior of proteins on (PAA-b-PNIPAM/PAH)n surfaces by varying the temperature and/or the pH of the medium, which seems to be intimately related to two key factors: (i) the ability of PNIPAM units to undergo conformational changes and (ii) the structural changes of the film made of weak polyelectrolytes. The simplicity of construction of these PNIPAM block copolymer-based LbL coatings on a large range of substrates, combined with their highly tunable features, make them ideal candidates to be employed for various biomedical applications requiring the control of protein adsorption.

[Evaluation of management of infarction in the Franche Comté province by the use of the Franche Comté Cardiology Registry, May 2005-May 2006]

RATIONALE

The management of acute infarction often necessitates a network of organisation between different centres, thus making it the object of an evaluation of professional practices (EPP). We report the experience in the Franche Comté province of an EPP at a regional level in the management of infarction.

METHODS

All of the patients admitted to 10 of the 11 centres in the region were included in a prospective survey. Quality indicators for acute and chronic care were defined, as well as scores, on the basis of use of treatments specified in guidelines.

RESULTS

Between May 2005 and May 2006, 1,170 patients were admitted. The patients' risk levels and quality scores were calculated. The rate of use of the quality indicators was higher in our survey than that observed in all of the published studies, except for the use of betablockers. The quality of care could therefore be considered as highly satisfactory. Comparison between the centres revealed some differences. Even after adjustment for the risk score on admission, the quality score for acute care was related to mortality at 1 month.

CONCLUSIONS

An EPP is possible for the management of infarction, on a regional scale such as in the province of Franche Comté. The acute quality score turned out to be an independent factor for mortality. The indicators showed that the quality of care was highly satisfactory, even though more progress could be made in the prescription of betablockers.

Lipase immobilization into porous chitoxan beads: activities in aqueous and organic media and lipase localization

Lipases were noncovalently immobilized in Chitoxan, a polyionic hydrogel obtained by complexation between chitosan and xanthan. The properties of free and immobilized lipases have been compared. In the aqueous medium, the activity was twice as high for immobilized lipases as for free lipases. Immobilized lipases in chitoxan were able to hydrolyze triacylglycerols in three distinct organic solvent media. At the microstructural level, lipases were not distributed uniformly in the chitoxan beads. Higher concentrations of lipase were found in the outer membrane-like layer of the beads, as compared with lower concentrations in the inner part of the beads.

Lack of agreement between left ventricular volumes and ejection fraction determined by two-dimensional echocardiography and contrast cineangiography in postinfarction patients

OBJECTIVE

To assess the agreement between left ventricular (LV) volumes and ejection fraction (EF) determined by two-dimensional echocardiography (2-D echo) and by cineangiography in postinfarction patients.

DESIGN

LV end-diastolic and end-systolic volumes indexed (EDVI and ESVI) to body surface area as well as EF were determined by both methods in all patients.

SETTING

Multicenter trial conducted in five university hospitals.

PATIENTS

63 patients, 61 male, two female, mean age 55.5 +/- 10.4 years, suffering from a recent myocardial infarction. Eighty-one pairs of measurements were available.

METHODS

The results of biplane 2-D echo measures, using apical four-chamber (4C) and two-chamber (2C) views were compared to those of a 30 degrees right anterior oblique cineangiography projection, using either the apical method of discs or the area-length 2-D echo method. Moreover, eyeball EF was estimated at 2-D echo and cineangiography, and was compared to the conventional methods. The agreement between results was assessed by the Bland and Altman method.

RESULTS

The agreement between 2-D echo and cineangiography results was poor. Mean differences (MD) were -21.8 (EDVI, ml/m(2)), -9.5 (ESVI, ml/m(2)), and -0.9 (EF, %), respectively for 2-D echo method of discs versus cineangiography, and -23.2, -9.3, and -5.7 for area-length 2-D echo versus cineangiography. For EF (%), MD was -3.6 for eyeball cineangiography versus cineangiography, -1.3 for eyeball 2-D echo versus method of discs, and +0.30 for eyeball 2-D echo versus area-length 2-D echo, respectively. Two-dimensional echo is likely to underestimate LV volumes compared to cineangiography, especially for largest volumes. Even for EF, discrepancies are large, with a lack of agreement of 21%-25% between conventional methods, but agreement is better between eyeball EF and usual methods.

CONCLUSIONS

Even with modern echocardiographic devices, agreement between 2-D echo and cineangiography-derived LV volumes and EF remains moderate, and both methods must not be considered interchangeable in clinical practice.

Planimetry of aortic valve area using multiplane transoesophageal echocardiography is not a reliable method for assessing severity of aortic stenosis

OBJECTIVE

To assess the reliability of aortic valve area planimetry by multiplane transoesophageal echocardiography (TOE) in aortic stenosis.

DESIGN

Study of the diagnostic value of aortic valve area planimetry using multiplane TOE, compared with catheterisation and the continuity equation, both being considered as criterion standards.

SETTING

University hospital.

PATIENTS

49 consecutive patients (29 male, 20 female, aged 44 to 82 years, average 66.6 (SD 8.5)), referred for haemodynamic evaluation of an aortic stenosis, were enrolled in a prospective study. From this sample, 37 patients were eligible for the final analysis.

METHODS

Transthoracic and multiplane transoesophageal echocardiograms were performed within 24 hours before catheterisation. At transthoracic echo, aortic valve area was calculated by the continuity equation. At TOE, the image of the aortic valve opening was obtained with a 30-65 degrees rotation of the transducer. Numerical dynamic images were stored on optical discs for off-line analysis and were reviewed by two blinded observers. Catheterisation was performed in all cases and aortic valve area was calculated by the Gorlin formula.

RESULTS

Feasibility of the method was 92% (48/52). The agreement between aortic valve area measured at TOE (mean 0.88 (SD 0.35) cm2) and at catheterisation (0.79 (0.24) cm2) was very poor. The same discrepancies were found between TOE and the continuity equation (0.72 (0.26) cm2). TOE planimetry overestimated aortic valve area determined by the two other methods. Predictive positive and negative values of planimetry to detect aortic valve area < 0.75 cm2 were 62% (10/16) and 43% (9/21) respectively.

CONCLUSIONS

Planimetry of aortic valve area by TOE is difficult and less accurate than the continuity equation for assessing the severity of aortic stenosis.

[Lithium poisoning]

A case of therapeutic overdosage in a 58-year-old woman is reported. Lithium plasma level was 3.7 mmol.l. All clinical and biological disturbances regressed in 3 days after controlled rehydration only. Aetiology, clinical picture, biological characteristics and treatment according to the severity of the lithium poisoning are discussed.

[A new treatment of deep venous thrombosis: low molecular weight heparin fractions. Randomized study]

Sixty-eight patients with acute deep vein thrombosis were allocated at random to two treatment groups. One group (n = 33) received a fixed dose of 750 anti-Xa units of a low molecular weight heparin (CY 222 Choay Institute); the other group (n = 35) received standard heparin in doses of 500 IU/kg/24 h. Both treatments were given for 10 days in two daily subcutaneous injections. A second phlebography was performed on the last day of treatment. No haemorrhagic complication was observed in the group treated with CY 222, as opposed to three cases of haemorrhage in the group treated with standard heparin. The initial phlebographic score and the location of deep vein thrombotic lesions were the same in both groups. Angiographic improvement, with more than 30% thrombolysis, was obtained at the end of treatment in 64% of patients in the CY 222 group and in 65% of patients in the standard heparin group (NS). In 2 patients treated with standard heparin the second phlebography showed extension of the thrombosis. The initial score remained unchanged in 1/3 of patients in both groups. The activated partial thromboplastin time was prolonged (2 or 3 fold the normal value) in the standard heparin group and unchanged in the CY 222 group. Anti-Xa activity was significantly higher in the CY 222 group than in the standard heparin group. It is concluded that CY 222 and standard heparin were equally effective in patients with deep vein thrombosis. However, haemorrhagic complications were more frequent with standard heparin that with CY 222.

Localization of technetium 99m-ethylenediamine-N,N'-bis(alpha-2-hydroxy-5-bromophenyl)acetic acid and technetium 99m-N-(2-mercapto-1-oxopropyl)glycine in hepatobiliary system

Two radiopharmaceuticals, technetium 99m-N-(2-mercapto-1-oxopropyl)glycine (99mTc-I) and technetium 99m-ethylenediamine-N,N'-bis(alpha-2-hydroxy-5-bromophenyl)acetic acid (99MTc-II), were prepared and evaluated in dogs, rabbits, and rats. Both agents gave good scintigraphic images of the liver and gallbladder in dogs. The cumulative amount of 99mTc-I and 99mTc-II excreted in the bile of dogs and the physiological disposition data in rats revealed slight, inconclusive differences in their distributions. However, the scintigraphic images and physiological disposition data in rabbits revealed gross differences in the distribution pattern of the two agents. The observed similarities in the biliary excretion of both agents in dogs and rats were attributed to the fact that these species are relatively good biliary excretors, and both agents therefore were excreted extensively. However, rabbits, which are poor biliary excretors relative to dogs and rats, excreted 99mTc-II more extensively than 99mTc-I because of the favorable molecular characteristics of 99mTc-II.

Faecal steroids and bacteria and large bowel cancer in Hong Kong by socio-economic groups

In a study of three socio-economic groups in Hong Kong, the high income group had a high faecal concentration of bile acids, especially the dihydroxy bile acids, compared to the low income group. The faecal bile acids were also more highly degraded. The faecal flora contained more bacteroides and fewer eubacteria. Very few of the clostridia able to dehydrogenate the steroid nucleus were isolated. An epidemiological study based on street blocks indicated that the high income group also have a higher incidence of cancer of the large bowel and of the breast. The results are discussed in terms of theories on the aetiology of large bowel cancer.

[Peroperative resuscitation in abdominal reoperations]

Resuscitation of these patients during operation is the only the logical continuation of their preparation. The authors therefore take up the preceding points while emphasizing: - checking vascular filling, by central venous pressure and hourly diuresis; - the necessity for a supply of carbohydrates, which is even more indispensable when the subjects were submitted to parenteral hyperalimentation previously; - the advantages of performing arterial blood gases in order to check artificial ventilation.