Predicting the distribution of whey protein fouling in a plate heat exchanger using the kinetic parameters of the thermal denaturation reaction of ß-lactoglobulin and the bulk temperature profiles.

Fouling of plate heat exchangers (PHE) is a severe problem in the dairy industry, notably because the relationship between the build-up of protein fouling deposits and the chemical reactions taking place in the fouling solution has not yet been fully elucidated. Experiments were conducted at pilot scale in a corrugated PHE, and fouling deposits were generated using a model ß-lactoglobulin (ß-LG) fouling solution for which the ß-LG thermal denaturation reaction constants had been previously determined experimentally. Then 18 different bulk temperature profiles within the PHE were imposed. Analysis of the fouling runs shows that the dry deposit mass per channel versus the ratio R=kunf/kagg (with kunf and kagg representing, respectively, the unfolding and aggregation rate constants computed from both the identification of the ß-LG thermal denaturation process and knowledge of the imposed bulk temperature profile into the PHE channel) is able to gather reasonably well the experimental fouling mass data into a unique master curve. This type of representation of the results clearly shows that the heat-induced reactions (unfolding and aggregation) of the various ß-LG molecular species in the bulk fluid are essential to capture the trend of the fouling mass distribution inside a PHE. This investigation also illustrates unambiguously that the release of the unfolded ß-LG (also called ß-LG molten globule) within the bulk fluid (and the absence of its consumption in the form of aggregates) is a key phenomenon that controls the extent of protein fouling as well as its location inside the PHE.

Granulomorphometry: a suitable tool for identifying hydrophobic and disulfide bonds in ß-lactoglobulin aggregates. Application to the study of ß-lactoglobulin aggregation mechanism between 70 and 95°C.

This work deals with the investigation of ß-lactoglobulin (ß-LG) aggregation by granulomorphometry. In the first part of this study, we showed that the binding interactions involved in aggregate structure could be identified by their appearance in granulomorphometric pictures. The reliability of this analytical approach was demonstrated by comparing the appearance of ß-LG aggregates in the presence and absence of a thiol-blocking agent (N-ethylmaleimide). The translucency of the aggregates was associated with hydrophobic interactions and their opacity was associated with disulfide bonds. We state, based on the morphology of the aggregates, along with the color of protein aggregates and insoluble materials, that hydrophobic interactions had a better water-holding capacity than disulfide bonds. Additionally, our results suggest that disulfide and hydrophobic bonds compete for ß-LG aggregate shaping. In the second part of this work, interesting features of granulomorphometry useful for identifying aggregate binding interactions were highlighted to clarify the effect of temperature on the aggregation mechanisms occurring in a ß-LG concentrate with a moderate calcium content (6.6mmol·L(-1)). Heat treatment experiments were performed between 70 and 95°C, and granulomorphometric measurements (aggregate size, aggregate number, and gray level of the picture) were conducted at different sampling times up to 4h. Results, which were interpreted in light of calculated ß-LG denaturation levels, revealed that the aggregation mechanism could be split into 2 steps. Initially, ß-LG denatured quickly, leading to fast ß-LG aggregation by disulfide bonds. The denaturation rate then declined, which drastically slowed the disulfide aggregation mechanism. From that point on, a second aggregation path became preponderant. It consisted of the agglomeration of small aggregates by hydrophobic interactions and resulted in the formation of large aggregates containing both interaction types. This second aggregation mechanism was clearly favored at high temperatures because it was not detected in our experiments at temperatures below 85°C.

[Insulin dependent diabetes and pregnancy: evaluation of the insulin pump]. / Diabète insulino-dépendant et grossesse: évaluation de la pompe à insuline.

OBJECTIVE: To evaluate the effectiveness of continuous insulin infusion (insulin pump) on the materno-foetal morbidity during pregnancy in patients with insulin-dependent diabetes mellitus. METHODS: A retrospective study from 1980 to 1991. SITE. Gynecology-Obstetrics Unit, University of Caen. POPULATION: Eighty-one patients with insulin-dependent diabetes mellitus known to be affected before their pregnancy were followed in the unit from 1980 to 1991. This population was divided into two groups: in the first group, an insulin pump was installed before 15 weeks of amenorrhoea (n = 36) and in the second group, conventional treatment was given with three daily injections of insulin or with a pump installed after 15 weeks of amenorrhoea (n = 45). RESULTS: In the first group with the insulin pump before 15 weeks, there was a higher proportion of severe diabetes, the first consultation occurred earlier, there were half as many cases of neonatal jaundice and the length of hospitalization during the first trimester of pregnancy was longer. There was no difference in Apgar scores, cord pH, birth weight and the proportion of foetal macrosomia, length of the hospitalization in the neonatality ward, rate of malformation, infection, low blood glucose and calcium, transitive respiratory distress and neonatal polycythaemia, length of hospitalization of the mother during the second and third week postpartum, the rate of urinary infection, high blood pressure, hydramnios during pregnancy, delivery route, haemoglobin Alc or fructosamine during pregnancy. There was no perinatal death. CONCLUSION: Although there was no significant difference in the results, which may be explained by the higher number of severe cases of diabetes in the first group, the use of the insulin pump did not appear to improve control of blood glucose levels, and thus to improve the materno-foetal prognosis, except by the bias of earlier attentive management of the pregnancy which led to better outcome.

[Surgical laparoscopy and pregnancy. Eight cases]. / Coelioscopie opératoire et grossesse. A propos de 8 observations.

Eight cases of abdominopelvic surgery including 7 conducted uniquely by laparoscopy point out certain questions concerning diagnosis and management with this technique. These 8 cases included 6 cysts of the ovary, 1 appendectomy and 1 myomectomy. The consequences related to the operation or the anaesthesia and the foetal consequences were evaluated retrospectively. In particular, laparoscopic surgery induces certain pathophysiological modifications which remain to be studied.

[Obstetric data in a population with postural changes during labor and delivery]. / Données obstétricales dans une population bénéficiant de variations posturales en cours de travail et d'accouchement.

INTRODUCTION: The aim of this study was to describe the potential impact of an active birth on classical obstetrical outcomes, as labor duration, cesarean section rate, couples and team satisfactions. MATERIAL AND METHODS: This observational study was prospective, monocentric and took place between May 2007 and February 2009 at the maternity ward of the University Hospital of Caen, France. An "active birth" was defined as an active latent-phase (having a change in position and/or a bath and/or a walk) followed by at least three changes in position during the active phase. The suggested positions were: lateral or dorsal decubitus, ROSA, on all fours, seated, standing and crouch. A position must have lasted at least 20 minutes to be considered. RESULTS: Out of the 1906 women included, 828 had an active birth (43.4%). Due to our definition of an "active birth", a "non-active birth" was significantly associated with a quicker labor. An "active birth" was associated with a decreased rate of cesarean section (OR=0.71; IC95%=[0.51-0.99]). The parturients satisfaction median was 9 on a scale of 0 to 10, the spouses'one was 10. Midwives were more satisfied when it was an "active birth". CONCLUSION: Significant associations with active births were highlighted, which would require to be validated by a randomised study. This practise plenty satisfied couples and midwives. In fact, no litterature exists to date. A consensus about the definition of an active birth is still necessary in order to lead to guidelines.

Mechanism of migration from agglomerated cork stoppers. Part 2: Safety assessment criteria of agglomerated cork stoppers for champagne wine cork producers, for users and for control laboratories.

Producers of cork for champagne and wine have to be certain the corks meet the requirements of the European Union Framework Directive, and comply with the evaluations of chemicals carried out in the European Union. To identify chemicals in cork with the potential to migrate, the different synthetic products on the market were classified based on their technical role and of the chemistry involved. The potential migrants in each class (adhesive for cork bodies, adhesive for cork disks, lubricants and surface treatments) were analysed spectroscopically and chromatographically. A general approach was proposed for the evaluation of each commercial chemical: the detailed composition was supplied and verified mainly by infrared spectroscopy, proton nuclear magnetic resonance spectroscopy ((1)H-NMR) and GC-MS. A procedure to determine primary aromatic amines, specifically for cork migrates, based on GC-MS was developed. These techniques focussed on migrants below 1000 g mol(-1), as higher molecular weight chemicals are not likely to pose a problem for public health. The products were also tested after polymerization. The analytical scheme included an analytical check of synthetic product formulation and identification of potential migrants, solvent extraction and analysis of cork extracts.

Bone loss after cardiac transplantation: effects of calcium, calcidiol and monofluorophosphate.

Of 203 patients who underwent cardiac transplantation and were given long-term treatment with cyclosporine and 0.3 mg/kg per day prednisone, 123 were studied prospectively for at least 6 months and 46 for up to 2 years to evaluate the effects on lumbar bone mineral density (BMD) and calcium metabolism of a combined therapy with calcium, calcidiol and disodium monofluorophosphate (MFP). The population was arbitrarily assigned to one of two groups. Group I consisted of patients who had a lumbar spine BMD Z score above -1.5 SD as compared with an age- and sex-matched population and no vertebral fractures. They received daily 1 g elemental calcium and 25 micrograms (1000 IU) calcidiol. Group II consisted of patients who received daily the same doses of calcium and calcidiol combined with 200 mg MFP, and was divided into two subgroups: (a) osteopenic subjects who had a lumbar spine BMD Z score below -1.5 SD without vertebral fractures and (b) osteoporotic subjects with vertebral fractures. If serum creatinine was higher than 140 mumol/l the daily dose of MFP was tapered to 100 mg. Fifty-four and 27 patients from group I and 38 and 19 patients from group II were followed respectively for 12 and 24 months. In both groups serum parathyroid hormone levels were significantly reduced from the twelfth month in parallel with a significant increase in serum 25-OHD levels. No decline in lumbar BMD occurred in non-osteopenic and non-osteoporotic patients (group 1) who received the calcium and calcidiol supplement. In group II, where MFP was added, a significant and linear increase in lumbar BMD was observed.(ABSTRACT TRUNCATED AT 250 WORDS)