Sustaining supercooled mixed phase via resonant oscillations of the order parameter

We investigate the dynamics of a first order transition when the order parameter field undergoes resonant oscillations, driven by a periodically varying parameter of the free energy. This parameter could be a background oscillating field as in models of pre-heating after inflation. In the context of condensed matter systems, it could be temperature $T$, or pressure, external electric/magnetic field etc. We show that with suitable driving frequency and amplitude, the system remains in a type of mixed phase, without ever completing transition to the stable phase, even when the oscillating parameter of the free energy remains below the corresponding critical value (for example, with oscillating temperature, $T$ always remains below the critical temperature $T_c$). This phenomenon may have important implications. In cosmology, it will imply prolonged mixed phase in a first order transition due to coupling with background oscillating fields. In condensed matter systems, it will imply that using oscillating temperature (or, more appropriately, pressure waves) one may be able to sustain liquids in a mixed phase indefinitely at low temperatures, without making transition to the frozen phase.Comment: 17 pages, 7 figures, Expanded version with more detail

Renal handling of polyamines

Polyamines are aliphatic, organic cations distributed in all living cells. They play an important role in cell proliferation, cell growth and synthesis and metabolism of macromolecules like nucleic acids and proteins. The three principal polyamines in mammalian cells are putrescine, spermidine and spermine. -- Polyamine excretion has been found to be increased in the urine of patients with various types of malignancies. Many workers have advocated the use of urinary polyamines as markers of malignancy and also for monitoring the effectiveness of cancer therapy. To use urinary polyamines for such a purpose it is important to understand how the kidney handles these substances, and to find out what is the source of the urinary polyamines. The present experiments were done to study these aspects of renal polyamine handling. -- In both male and female rats, putrescine was the major polyamine excreted, followed by spermidine and smaller amounts of spermine and the acetylated polyamines. No cadaverine was detected in the urine of any of these rats on a polyamine-free diet. Equilibrium dialysis studies in vitro showed that about 8% of putrescine and 16% of spermidine are non-covalently bound to plasma proteins, therefore, most of the putrescine and spermidine should be filterable. When the excreted load of spermidine was compared to the probable filtered load, using the free spermidine concentration, it was found that only 0.6-1.5% of the spermidine was excreted. The negligible arteriovenous difference in whole blood and plasma indicates that almost all of the spermidine entering the glomerulus is returned to the renal circulation. Thus reabsorption is the predominant fate of the spermidine filtered at the glomerular membrane. On the other hand, a higher proportion of the filtered putrescine was excreted, although this still only ranged from 14% (female) to 29% (male) of the probable filtered load in untreated rats. Much more putrescine is removed from the red blood cells as they pass through the kidney than what is excreted. The metabolic fate of this putrescine is not known. -- In order to test whether reabsorption occurred in the proximal tubule, female rats were treated with maleate to produce an experimental Fanconi syndrome characterized by a generalized disruption of the reabsorption processes in the proximal renal tubule. Polyamine excretion was compared with that from saline-treated control rats. Maleate treatment for four hours produced polyuria, glucosuria and aminoaciduria. There was a significant drop in the plasma spermidine level and a significant decrease in the filtered load of spermidine. The plasma putrescine delivery and the plasma level remained unaltered due to maleate treatment. There was a significant decrease in the percentage reabsorption of both putrescine and spermidine. It was concluded that maleate interferes with polyamine reabsorption as it does with reabsorption of amino acids and other substances by the proximal tubule. Spermidine reabsorption by the kidney may play an important role in maintaining its plasma level; an interference of reabsorption producing excess excretion causes a failure to maintain plasma spermidine levels. On the other hand, plasma putrescine level may have a tighter regulation, which prevents a decrease in plasma concentration even when its excretion is increased due to interference in reabsorption

Comparison of hemodynamic and analgesic effects of interscalene block with bupivacaine versus bupivacaine-dexmedetomidine combination for shoulder arthroscopy under general anesthesia

Background: The interscalene block in shoulder arthroscopy is a well-established procedure. Many drugs have been used as adjuvants to local anesthetics to increase the quality of block in regional anesthesia, with variable results. Aims and Objectives: The present study was designed to evaluate the effect of dexmedetomidine as an adjuvant to bupivacaine during interscalene block in terms of intraoperative hemodynamic changes and postoperative analgesia. Materials and Methods: Thirty patients, aged 20–55 years of either sex, American Society of Anesthesiologists physical status I-II, scheduled for shoulder arthroscopic surgery for <2 h, were allocated into two equal groups to receive inj. bupivacaine (0.25%) with inj. dexmedetomidine 1 μg/kg (Group BD, n=15) or inj. bupivacaine (0.25%) with 1 mL normal saline (Group BS, n=15), total volume 20 mL in each case. After settlement of the interscalene block, both groups received general anesthesia as per standard protocol. Hemodynamic parameters (heart rate [HR] and systolic blood pressure [SBP]) were assessed in the intraoperative period, and postoperative pain was assessed using a visual analog scale score in the postoperative period at stipulated time points. Results: The mean values of HR and SBP were considerably low at all observed time points in the intraoperative period (i.e., at 10 min, 30 min, 60 min, 90 min, and120 min), in comparison with the saline group (P<0.0001). VAS scores between the two groups were considerably lower only at 8, 12, and 18 h in patients receiving dexmedetomidine (P<0.001). Conclusion: Dexmedetomidine as an adjuvant with bupivacaine can achieve a better hemodynamic profile (lower HR and SBP) in the intraoperative period. Also, the use of dexmedetomidine provides better postoperative analgesia profiles in the later part of the postoperative period (8–18 h), and the effect usually wanes by 24 h

Adipocyte fetuin-A contributes to macrophage migration into adipose tissue and polarization of macrophages

Macrophage infiltration into adipose tissue during obesity and their phenotypic conversion from anti-inflammatory M2 to proinflammatory M1 subtype significantly contributes to develop a link between inflammation and insulin resistance; signaling molecule(s) for these events, however, remains poorly understood. We demonstrate here that excess lipid in the adipose tissue environment may trigger one such signal. Adipose tissue from obese diabetic db/db mice, high fat diet-fed mice, and obese diabetic patients showed significantly elevated fetuin-A (FetA) levels in respect to their controls; partially hepatectomized high fat diet mice did not show noticeable alteration, indicating adipose tissue to be the source of this alteration. In adipocytes, fatty acid induces FetA gene and protein expressions, resulting in its copious release. We found that FetA could act as a chemoattractant for macrophages. To simulate lipid-induced inflammatory conditions when proinflammatory adipose tissue and macrophages create a niche of an altered microenvironment, we set up a transculture system of macrophages and adipocytes; the addition of fatty acid to adipocytes released FetA into the medium, which polarized M2 macrophages to M1. This was further confirmed by direct FetA addition to macrophages. Taken together, lipid-induced FetA from adipocytes is an efficient chemokine for macrophage migration and polarization. These findings open a new dimension for understanding obesity-induced inflammation

Neisseria gonorrhoeae lipooligosaccharide glycan epitopes recognized by bactericidal IgG antibodies elicited by the meningococcal group B-directed vaccine, MenB-4C

IntroductionOuter membrane vesicles (OMVs) of Neisseria meningitidis in the group B-directed vaccine MenB-4C (BexseroR) protect against infections with Neisseria gonorrhoeae. The immunological basis for protection remains unclear. N. meningitidis OMV vaccines generate human antibodies to N. meningitidis and N. gonorrhoeae lipooligosaccharide (LOS/endotoxin), but the structural specificity of these LOS antibodies is not defined.MethodsTen paired human sera obtained pre- and post-MenB-4C immunization were used in Western blots to probe N. meningitidis and N. gonorrhoeae LOS. Post-MenB-4C sera (7v5, 19v5, and 17v5), representing individual human variability in LOS recognition, were then used to interrogate structurally defined LOSs of N. meningitidis and N. gonorrhoeae strains and mutants and studied in bactericidal assays.Results and discussionPost-MenB-4C sera recognized both N. meningitidis and N. gonorrhoeae LOS species, ~10% of total IgG to gonococcal OMV antigens. N. meningitidis and N. gonorrhoeae LOSs were broadly recognized by post-IgG antibodies, but with individual variability for LOS structures. Deep truncation of LOS, specifically a rfaK mutant without α-, β-, or γ-chain glycosylation, eliminated LOS recognition by all post-vaccine sera. Serum 7v5 IgG antibodies recognized the unsialyated L1 α-chain, and a 3-PEA-HepII or 6-PEA-HepII was part of the conformational epitope. Replacing the 3-PEA on HepII with a 3-Glc blocked 7v5 IgG antibody recognition of N. meningitidis and N. gonorrhoeae LOSs. Serum 19v5 recognized lactoneotetrose (LNT) or L1 LOS-expressing N. meningitidis or N. gonorrhoeae with a minimal α-chain structure of Gal-Glc-HepI (L8), a 3-PEA-HepII or 6-PEA-HepII was again part of the conformational epitope and a 3-Glc-HepII blocked 19v5 antibody binding. Serum 17v5 LOS antibodies recognized LNT or L1 α-chains with a minimal HepI structure of three sugars and no requirement for HepII modifications. These LOS antibodies contributed to the serum bactericidal activity against N. gonorrhoeae. The MenB-4C vaccination elicits bactericidal IgG antibodies to N. gonorrhoeae conformational epitopes involving HepI and HepII glycosylated LOS structures shared between N. meningitidis and N. gonorrhoeae. LOS structures should be considered in next-generation gonococcal vaccine design

Effect of Cold Stress on Pyridostigmine Pretreated Rats Exposed to an Organophosphorous Compound

Context: Pyridostigmine bromide (PB) is a quaternary ammonium compound and has been approved as a pretreatment drug against toxic organophosphorous (OP) compounds. The stressful demands of modern military activity include a broad range of activities at extreme cold temperatures along with various physical activities. Objective: The effect of “sign free” dose of PB (0.075 mg/kg body weight) against a toxic OP compound diisopropyl fluorophosphate (DFP) was reassessed in rats. Electrocardiographic (ECG) studies in hypothermic and pretreatment conditions were undertaken to assess the cardioprotective role of PB. Total Antioxidant Status (TAS) was quantified to assess the degree of oxidative stress imposed under such conditions. Possible protective role of pyridostigmine in rat lymphocytes was also determined.Materials&amp; Methods: TAS was estimated spectrophotometrically and the expression of interferon-γ (IFNγ) was measured by Fluorescence Activated Cell Sorting. ECG was monitored by standard protocol.Results: ECG recording showed that the PR and QT interval progressively increased along with widening of QRS complex. There was a progressive fall in heart rate as the body temperature decreased. TAS significantly decreased (p≤0.001) in hypothermic conditions and when pretreated with sign free dose of PB before cold induction (p≤0.001). Following immunostaining of lymphocytes by FITC conjugated mouse anti-rat IFNγ monoclonal antibody, 9.1% of lipopolysaccharide elicited parent cells showed positive IFNγ expression. Hypothermic stress inhibited IFNγ expression (3.6% of parent cells) which was recovered to 6.8% upon pre-treatment with sign-free dose of pyridostigmine. Conclusion: This study is indicative of a possible protective role of PB against hypothermic stress

Formation and Collapse of False Vacuum Bubbles in Relativistic Heavy-Ion Collisions

It is possible that under certain situations, in a relativistic heavy-ion collision, partons may expand out forming a shell like structure. We analyze the process of hadronization in such a picture for the case when the quark-hadron transition is of first order, and argue that the inside region of such a shell must correspond to a supercooled (to $T = 0$) deconfined vacuum. Hadrons from that region escape out, leaving a bubble of pure deconfined vacuum with large vacuum energy. This bubble undergoes relativistic collapse, with highly Lorentz contracted bubble walls, and may concentrate the entire energy into extremely small regions. Eventually different portions of bubble wall collide, with the energy being released in the form of particle production. Thermalization of this system can lead to very high temperatures. With a reasonably conservative set of parameters, at LHC, the temperature of the hot spot can reach as high as 3 GeV, and well above it with more optimistic parameters. Such a hot spot can leave signals like large $P_T$ partons, dileptons, and enhanced production of heavy quarks. We also briefly discuss a speculative possibility where the electroweak symmetry may get restored in the highly dense region resulting from the decay of the bubble wall via the phenomenon of non-thermal symmetry restoration (which is usually employed in models of pre-heating after inflation). If that could happen then the possibility may arise of observing sphaleron induced baryon number violation in relativistic heavy-ion collisions.Comment: 32 pages, 9 figures, title changed, discussion added about equilibration of decay products of bubble wall, discussions of baryon violation significantly modified, new references added. (Version to appear in Nucl.Phys.A