Dynamics of uncrystallized water and protein in hydrated elastin studied by thermal and dielectric techniques.

Dynamics of uncrystallized water and protein was studied in hydrated pellets of the fibrous protein elastin in a wide hydration range (0 to 23wt.%), by differential scanning calorimetry (DSC), thermally stimulated depolarization current technique (TSDC) and dielectric relaxation spectroscopy (DRS). Additionally, water equilibrium sorption-desorption measurements (ESI) were performed at room temperature. The glass transition of the system was studied by DSC and its complex dependence on hydration water was verified. A critical water fraction of about 18wt.% was found, associated with a reorganization of water in the material. Three dielectric relaxations, associated to dynamics related to distinct uncrystallized water populations, were recorded by TSDC and DRS. The low temperature secondary relaxation of hydrophilic polar groups on the protein surface triggered by hydration water for almost dry samples contains contributions from water molecules themselves at higher water fractions (ν relaxation). This particular relaxation is attributed to water molecules in the primary and secondary hydration shells of the protein fibers. At higher temperatures and for water fraction values equal to or higher than 10wt.%, a local relaxation of water molecules condensed within small openings in the interior of the protein fibers was recorded. The evolution of this relaxation (w relaxation) with hydration level results in enhanced cooperativity at high water fraction values, implying the existence of "internal" water confined within the protein structure. At higher temperatures a relaxation associated with water dynamics within clusters between fibers (p relaxation) was also recorded, in the same hydration range.

Protein and water dynamics in bovine serum albumin-water mixtures over wide ranges of composition.

Dielectric dynamic behavior of bovine serum albumin (BSA)-water mixtures over wide ranges of water fractions, from dry protein until 40 wt % in water, was studied through dielectric relaxation spectroscopy (DRS). The α relaxation associated with the glass transition of the hydrated system was identified. The evolution of the low temperature dielectric relaxation of small polar groups of the protein surface with hydration level results in the enhancement of dielectric response and the decrease of relaxation times, until a critical water fraction, which corresponds to the percolation threshold for protonic conductivity. For water fractions higher than the critical one, the position of the secondary ν relaxation of water saturates in the Arrhenius diagram, while contributions originating from water molecules in excess (uncrystallized water or ice) follow separate relaxation modes slower than the ν relaxation.

Management of pregnancy and delivery of a patient with malfunctioning ventriculoperitoneal shunt.

The use of ventriculoperitoneal shunts increased the life expectancy of many women with hydrocephalus who are able to reach childbearing age. It is believed that pregnancy may be associated with shunt malfunction and the management of pregnant women with a malfunctioning ventriculoperitoneal shunt is a challenging medical condition for the anaesthetist, the obstetrician and the neurosurgeon. We report on a case of a 35-year-old primiparous woman who underwent a scheduled caesarean delivery at 30 weeks' gestation due to deteriorating neurological condition during pregnancy. The patient had a history of astrocytoma resection in the past and placement of a ventriculoperitoneal shunt due to obstructive hydrocephalus. She had a normal life without neurological deficits until the 18th week of gestation, when the first neurological symptoms appeared. An MRI was done that showed significant dilatation of the fourth ventricle and it was believed that the shunt was not functioning properly so the patient's symptoms were present because of raised intracranial pressure. In the 30th week of gestation, she had a caesarean delivery under epidural anaesthesia and she gave birth to a live female infant. Her neurological condition started improving 48 h after delivery and the symptoms gradually regressed. At 20 days after surgery she was discharged from hospital. The presence of a ventriculoperitoneal shunt is not a contraindication for pregnancy. Maternal shunt dependency carries a relatively high incidence of complications for some patients, e.g. shunt malfunction due to raised intraabdominal pressure caused by the gravid uterus. The results of pregnancies and deliveries in women with pre-existing ventriculoperitoneal shunts are favourable if there is proper management.

Glass transition and dynamics in BSA-water mixtures over wide ranges of composition studied by thermal and dielectric techniques.

Protein-water dynamics in mixtures of water and a globular protein, bovine serum albumin (BSA), was studied over wide ranges of composition, in the form of solutions or hydrated solid pellets, by differential scanning calorimetry (DSC), thermally stimulated depolarization current technique (TSDC) and dielectric relaxation spectroscopy (DRS). Additionally, water equilibrium sorption isotherm (ESI) measurements were performed at room temperature. The crystallization and melting events were studied by DSC and the amount of uncrystallized water was calculated by the enthalpy of melting during heating. The glass transition of the system was detected by DSC for water contents higher than the critical water content corresponding to the formation of the first sorption layer of water molecules directly bound to primary hydration sites, namely 0.073 (grams of water per grams of dry protein), estimated by ESI. A strong plasticization of the T(g) was observed by DSC for hydration levels lower than those necessary for crystallization of water during cooling, i.e. lower than about 0.3 (grams of water per grams of hydrated protein) followed by a stabilization of T(g) at about -80°C for higher water contents. The α relaxation associated with the glass transition was also observed in dielectric measurements. In TSDC a microphase separation could be detected resulting in double T(g) for some hydration levels. A dielectric relaxation of small polar groups of the protein plasticized by water, overlapped by relaxations of uncrystallized water molecules, and a separate relaxation of water in the crystallized water phase (bulk ice crystals) were also recorded.

Management of acute severe hyperlipidemic pancreatitis.

BACKGROUND/AIM: Hypertriglyceridemia is rare and can provoke acute severe hyperlipidemic pancreatitis when triglyceride levels exceed 11.3 mmol/l. In 10 patients we evaluated the therapeutic guidelines for severe hyperlipidemic pancreatitis. METHODS: Ten patients (8 men and 2 women) were admitted to the intensive care unit with a diagnosis of acute severe hyperlipidemic pancreatitis. They underwent standard treatment. Heparin, insulin and antihyperlipidemic drugs were used to lower the triglyceride levels. The patients underwent plasmapheresis within 48 h of admission, and fat-free parenteral nutrition was used. Two of the patients underwent surgery because of infection of necrotic segments. RESULTS: Standard treatment was essential for all the patients but plasmapheresis was the procedure that lowered the triglyceride and lipid levels in all cases. It improved abdominal pain, clinical state, and signs and symptoms of the disease. Two patients underwent surgery due to infection of the necrotic segments and one of them died. Follow-up lasted 4-54 months with no recurrences of pancreatitis. CONCLUSION: Our study shows that standard treatment is essential, but plasmapheresis successfully lowered lipid levels with no complications and relieved the patients from the symptoms in the acute phase of the disease. Hyperlipidemic pancreatitis should initially be treated conservatively. Plasmapheresis is a method that has lately been used successfully for hyperlipidemic pancreatitis. It seems that all therapeutic measures should be applied as early as possible, within the first 48 h.