Phase behavior and glass transition of 1,2-dioleoylphosphatidylethanolamine (DOPE) dehydrated in the presence of sucrose

The effect of sucrose on the phase behavior of 1,2-dioleoylphosphatidylethanolamine (DOPE) as a function of hydration was studied using differential scanning calorimetry and X-ray diffraction. DOPE/sucrose/water dispersions were dehydrated at osmotic pressures (Pi) ranging from 2 to 300 MPa at 30 degrees C and 0 degrees C. The hexagonal II-to-lamellar gel (H(II)-->L(beta)) thermotropic phase transition was observed during cooling in mixtures dehydrated at Pior=57 MPa, the H(II)-->L(beta) thermotropic phase transition was precluded when sucrose entered the rigid glassy state while the lipid was in the H(II) phase. Sucrose also hindered the H(II)-to-lamellar crystalline (L(c)), and H(II)-to-inverted ribbon (P(delta)) lyotropic phase transitions, which occurred in pure DOPE. Although the L(c) phase was observed in dehydrated 2:1 (mole ratio) DOPE/sucrose mixtures, it did not form in mixtures with higher sucrose contents (1:1 and 1:2 mixtures). The impact of sucrose on formation of the ordered phases (i.e., the L(c), L(beta), and P(delta) phases) of DOPE was explained as a trapping of DOPE in a metastable H(II) phase due to increased viscosity of the sucrose matrix. In addition, a glass transition of DOPE in the H(II) phase was observed, which we believe is the first report of a glass transition in phospholipids.     

Siberian sturgeon <Emphasis Type="Italic">Acipenser baerii</Emphasis> in the River Pechora

The paper reports the first reliable capture since the last 150 yr of two sturgeons in the basin of the River Pechora. Both specimens had the systematic traits of the Siberian sturgeon Acipenser baerii but differed significantly in external morphology. Data on biological traits and morphological parameters of the fish are presented. It is suggested that Pechora Basin should be included into the range of the Siberian sturgeon. Occurrences of the Siberian sturgeon in Pechora are discussed.     

Investigation of Design Space for Freeze-Drying: Use of Modeling for Primary Drying Segment of a Freeze-Drying Cycle

In this work, we explore the idea of using mathematical models to build design space for the primary drying portion of freeze-drying process. We start by defining design space for freeze-drying, followed by defining critical quality attributes and critical process parameters. Then using mathematical model, we build an insilico design space. Input parameters to the model (heat transfer coefficient and mass transfer resistance) were obtained from separate experimental runs. Two lyophilization runs are conducted to verify the model predictions. This confirmation of the model predictions with experimental results added to the confidence in the insilico design space. This simple step-by-step approach allowed us to minimize the number of experimental runs (preliminary runs to calculate heat transfer coefficient and mass transfer resistance plus two additional experimental runs to verify model predictions) required to define the design space. The established design space can then be used to understand the influence of critical process parameters on the critical quality attributes for all future cycles.     

Phase diagram of 1,2-dioleoylphosphatidylethanolamine (DOPE):water system at subzero temperatures and at low water contents.

The phase behavior of partially hydrated 1, 2-dioleoylphosphatidylethanolamine (DOPE) has been studied using differential scanning calorimetry and X-ray diffraction methods together with water sorption isotherms. DOPE liposomes were dehydrated in the H(II) phase at 29 degrees C and in the L(alpha) phase at 0 degrees C by vapor phase equilibration over saturated salt solutions. Other samples were prepared by hydration of dried DOPE by vapor phase equilibration at 29 degrees C and 0 degrees C. Five lipid phases (lamellar liquid crystalline, L(alpha); lamellar gel, L(beta); inverted hexagonal, H(II); inverted ribbon, P(delta); and lamellar crystalline, L(c)) and the ice phase were observed depending on the water content and temperature. The ice phase did not form in DOPE suspensions containing <9 wt% water. The L(c) phase was observed in samples with a water content of 2-6 wt% that were annealed at 0 degrees C for 2 or more days. The L(c) phase melted at 5-20 degrees C producing the H(II) phase. The P(delta) phase was observed at water contents of <0.5 wt%. The phase diagram, which includes five lipid phases and two water phases (ice and liquid water), has been constructed. The freeze-induced dehydration of DOPE has been described with the aid of the phase diagram.     

Surface Acidity and Solid-State Compatibility of Excipients with an Acid-Sensitive API: Case Study of Atorvastatin Calcium

The objectives of this study were to measure the apparent surface acidity of common excipients and to correlate the acidity with the chemical stability of an acid-sensitive active pharmaceutical ingredient (API) in binary API-excipient powder mixtures. The acidity of 26 solid excipients was determined by two methods, (i) by measuring the pH of their suspensions or solutions and (ii) the pH equivalent (pH_eq) measured via ionization of probe molecules deposited on the surface of the excipients. The chemical stability of an API, atorvastatin calcium (AC), in mixtures with the excipients was evaluated by monitoring the appearance of an acid-induced degradant, atorvastatin lactone, under accelerated storage conditions. The extent of lactone formation in AC-excipient mixtures was presented as a function of either solution/suspension pH or pH_eq. No lactone formation was observed in mixtures with excipients having pH_eq > 6, while the lactone levels were pronounced (> 0.6% after 6 weeks at 50°C/20% RH) with excipients exhibiting pH_eq < 3. The three pH_eq regions (> 6, 3–6, and < 3) were consistent with the reported solution pH-stability profile of AC. In contrast to the pH_eq scale, lactone formation did not show any clear trend when plotted as a function of the suspension/solution pH. Two mechanisms to explain the discrepancy between the suspension/solution pH and the chemical stability data were discussed. Acidic excipients, which are expected to be incompatible with an acid-sensitive API, were identified based on pH_eq measurements. The incompatibility prediction was confirmed in the chemical stability tests using AC as an example of an acid-sensitive API.

Electronic supplementary material

The online version of this article (doi:10.1208/s12249-014-0231-7) contains supplementary material, which is available to authorized users.KEY WORDS: acidity, atorvastatin, excipients, pH indicators, solid-state stability     

A molecular characterization of the charismatic Faroe house mouse

Faroe house mice are a ‘classic’ system of rapid and dramatic morphological divergence highlighted by J. S. Huxley during the development of the Modern Synthesis. In the present study, we characterize these charismatic mice using modern molecular techniques, examining specimens from all Faroe islands occupied by mice. The aims were to classify the mice within the modern house mouse taxonomy (i.e. as either Mus musculus domesticus or Mus musculus musculus) using four molecular markers and a morphological feature, and to examine the genetic diversity and possible routes of colonization using mitochondrial (mt) control region DNA sequences and microsatellite data (15 loci). Mice on the most remote islands were characterized as M. m. domesticus and exhibited exceptionally low genetic diversity, whereas those on better connected islands were more genetically diverse and had both M. m. musculus and M. m. domesticus genetic elements, including one population which was morphologically M. m. musculus‐like. The mtDNA data indicate that the majority of the mice had their origins in south‐western Norway (or possibly southern Denmark/northern Germany), and probably arrived with the Vikings, earlier than suggested by Huxley. The M. m. musculus genetic component appears to derive from recent mouse immigration from Denmark. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 471–482.     

Identification of structural DNA variations in human cell cultures after long-term passage

Random amplified polymorphic DNA (RAPD) analysis was adapted for genomic identification of cell cultures and evaluation of DNA stability in cells of different origin at different culture passages. DNA stability was observed in cultures after no more than 5 passages. Adipose-derived stromal cells demonstrated increased DNA instability. RAPD fragments from different cell lines after different number of passages were cloned and sequenced. The chromosomal localization of these fragments was identified and single-nucleotide variations in RAPD fragments isolated from cell lines after 8–12 passages were revealed. Some of them had permanent localization, while most variations demonstrated random distribution and can be considered as de novo mutations.     

Recommended Best Practices for Process Monitoring Instrumentation in Pharmaceutical Freeze Drying—2017

Recommended best practices in monitoring of product status during pharmaceutical freeze drying are presented, focusing on methods that apply to both laboratory and production scale. With respect to product temperature measurement, sources of uncertainty associated with any type of measurement probe are discussed, as well as important differences between the two most common types of temperature-measuring instruments—thermocouples and resistance temperature detectors (RTD). Two types of pressure transducers are discussed—thermal conductivity-type gauges and capacitance manometers, with the Pirani gauge being the thermal conductivity-type gauge of choice. It is recommended that both types of pressure gauge be used on both the product chamber and the condenser for freeze dryers with an external condenser, and the reasoning for this recommendation is discussed. Developing technology for process monitoring worthy of further investigation is also briefly reviewed, including wireless product temperature monitoring, tunable diode laser absorption spectroscopy at manufacturing scale, heat flux measurement, and mass spectrometry as process monitoring tools.     

The Distribution of Some Hydrolytic Enzymes in the Wheat Seed

A histochemical study of dry and germinated wheat embryos andseeds has been made to identify the sites of activity of 3'-and 5'-nucleotidases, phosphatases, lipase, and esterase. Theenzymes all showed the same distribution, with the coleorhizaas the most prominent site of activity in the dry embryo, especiallywhen compared with the adjacent roots with very low activity.Investigations of the whole seed after 24 h germination showeda very high activity in the aleurone cells and high activitiesin the scutellum and coleorhiza. The epithelium and provasculartissues of the scutellum showed moderate to low activity whilethe endosperm had little or none. Hydrolase activity also wasfound in the testa. The function of the coleorhiza. as firstfood reserve for the roots and its location at the most importantsite of water entry, is discussed.