High flow nasal oxygen therapy for COVID 19: an unusual complication

Background

Acute hypoxemic respiratory failure is the most common complication of COVID 19 infection. Newer ways for oxygen therapy were explored during this pandemic. High flow nasal oxygenation (HFNO) emerged as a novel technique for oxygenation and prevented the need for invasive mechanical ventilation during hypoxia among COVID patients. Using high flow oxygen dries the nasal mucosa and leads to skin disruption. We are presenting this case as this complication has not been reported anywhere to our knowledge.

Case presentation

Here we present a case of a 62-year-old male, who was on HFNO for a long time as a part of treatment for COVID 19 and developed ulceration in the nasal septa. Patient belonged to a geriatric age group and had diabetes mellitus. Close monitoring by ICU (intensive care unit) staff was a big problem during this pandemic. Daily physical assessment, good nutrition, and daily dressing with plastic surgery consultation helped treat our patient.

Conclusions

Geriatric patients with other co-morbidities are vulnerable to mucosal injury. Even in COVID era, everyday general physical surveillance is very vital in such patients to prevent these complications. During this pandemic close monitoring of patients suffered due to scarcity of ICU staff. In spite of that, it is a must to ensure daily physical surveillance and good supplemental nutrition especially in geriatric patients.

Abstract P2-02-14: Metabolic regulation and drug resistance in c-Src activated triple negative breast cancer

c-Src (Src) is a proto-oncogene involved in signaling that culminates in the control of multiple biological functions. Src is also one of the most frequently upregulated pathways in triple negative breast cancer (TNBC). Dysregulation of Src has been detected in TNBC and is strongly associated with tumor metastasis and poor prognosis. However, even after promising preclinical studies, Src inhibitors did not show major clinical advantage in unselected TNBC populations. We have previously published that metastatic TNBC has high energy-dependency to mitochondrial fatty acid beta-oxidation (FAO) and FAO activates Src by inducing autophosphorylation at Y419. However, our recent analysis suggests that as observed with the Src inhibitors, TNBC tumors treated with FAO inhibitors also develop drug-resistance and continue tumor growth. Evaluation of their drug resistance mechanism revealed that while short-term inhibition of FAO or Src induces autophagic and apoptotic cell deaths, long-term inhibition results in autophagy-mediated drug resistance and survival. Further analyses suggest that FAO and Src inhibitors activate mitogen-activated protein (MAP) kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) pathway via the induction of cellular reactive oxygen species (ROS) in TNBC. Activated MEK/ERK then induces survival pathways for drug resistance and tumor survival. Validation of in vitro findings using in vivo TNBC models confirmed that combination of FAO/Src inhibitors with MEK/ERK inhibitors can provide significant benefit to overcome the therapeutic resistance of TNBC. These findings open-up new therapeutic opportunities to manage TNBC patients with currently non-targetable metastatic tumors.

Citation Format: Jung KH, Park JH, Sirupangi T, Jia D, Gandhi N, Pudakalakatti S, Elswood J, Porter W, Putluri N, Zhang XH-F, Chen X, Bhattacharya PK, Creighton CJ, Lewis MT, Rosen JM, Wong L-JC, Das GM, Osborne CK, Rimawi MF, Kaipparettu BA. Metabolic regulation and drug resistance in c-Src activated triple negative breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-02-14.

Spectrum of Glomerular Diseases in Adults: A Study from North Eastern India

AIMS AND OBJECTIVES

To study the clinical profile of patients with glomerular diseases and to study pattern of glomerular diseases in adults.

METHODOLOGY

A hospital based retrospective observational study from North Eastern India that includes biopsy proven glomerular disease (GD) in adults. Patients with inadequate biopsy sampling; incomplete medical data and biopsy of transplanted kidney were excluded.

RESULTS AND OBSERVATIONS

A total of 102 patients were included of which 25 (24.5%) were male and 77(75.5%) were female with M: F ratio of 0.32:1. The mean age of presentation was 30.6 years. Nephrotic syndrome (57.8%) was the commonest clinical diagnosis followed by acute nephritic syndrome (31.4%), unexplained AKI (5.9%), unexplained CKD with normal kidney size (2.9%) and asymptomatic urine abnormality (1.9%). On histo-pathological analysis primary GD and secondary GD was diagnosed in 46(45.1%) and 53(52.0%) respectively. Overall Lupus nephritis (LN) was found to be the commonest (41.2%) GD. Among the primary GD, MCD (11.8%) was the most frequent followed by MPGN (10.8%), Membranous Nephropathy, (5.8%), IgA nephropathy (5.8%) and Focal segmental glomerulosclerosis (5.8%). Three (2.9%) patients did not have any specific diagnosis and were labelled as chronic glomerulo- nephritis..

CONCLUSIONS

As the pattern of glomerular disease varies from one region to another, the pattern of glomerular disease in the north eastern India also varies from the other regions of India. Nephrotic syndrome remains the most common indication of renal biopsy in this region similar to the other parts of India. Unlike other studies from outside North Eastern India, this study show that females are more commonly involved with majority of them having secondary GD and this is due to LN which was diagnosed as the most common GD in the present study.

The TERI ENVIS Centre: an Indian information centre on renewable energy and the environment

Realizing the dearth of environmental information in India, the Ministry of Environment and Forests established an Environmental Information System (ENVIS) as a plan programme in December 1982. The focus of ENVIS since its inception has been on providing environmental information to decision makers, policy planners, scientists and engineers, research workers, etc., all over India. Under this programme a few organizations were identified as centres of excellence and requested to host ENVIS Centres on various environmental areas. The Energy and Resources Institute (TERI) in New Delhi was identified as the ENVIS Centre on Renewable Energy and Environment. This paper highlights the activities performed at the TERI ENVIS Centre and the various tools used, such as web sites, publications, etc., to disseminate information among researchers, consultants and policy makers. It also outlines future courses of action for the Centre.

Scrub typhus meningoencephalitis, a diagnostic challenge for clinicians: A hospital based study from North-East India

Central nervous system (CNS) involvement is a known complication of scrub typhus which range from mild meningitis to frank meninigoencephalitis.

Chemical reaction-induced multi-molecular polarization (CRIMP)

Here we present a novel hyperpolarization method, Chemical Reaction-Induced Multi-molecular Polarization (CRIMP), which could be applied to the study of several in vivo processes simultaneously including glycolysis, TCA cycle, fatty acid synthesis and pH mapping. Through the use of non-enzymatic decarboxylation, we generate four hyperpolarized imaging agents from hyperpolarized 1,2-(13)C pyruvic acid.

Observation of standing waves of electron-hole sound in a photoexcited semiconductor

Three-dimensional multicomponent plasmas composed of species with very different masses support a new branch of charge-density fluctuations known as acoustic plasmons. Here, we report on an ultrafast optical method to generate and probe coherent states of acoustic plasmons in a slab of GaAs, which relies on strong photoexcitation to create a large population of light electrons and heavy holes. Consistent with the random-phase-approximation theory, the data reveal standing plasma waves confined to these slabs, similar to those of conventional sound but with associated velocities that are significantly larger.

In vivo magnetic resonance imaging of hyperpolarized silicon particles

Silicon-based micro- and nanoparticles have gained popularity in a wide range of biomedical applications due to their biocompatibility and biodegradability in vivo, as well as their flexible surface chemistry, which allows drug loading, functionalization and targeting. Here, we report direct in vivo imaging of hyperpolarized (29)Si nuclei in silicon particles by magnetic resonance imaging. Natural physical properties of silicon provide surface electronic states for dynamic nuclear polarization, extremely long depolarization times, insensitivity to the in vivo environment or particle tumbling, and surfaces favourable for functionalization. Potential applications to gastrointestinal, intravascular and tumour perfusion imaging at subpicomolar concentrations are presented. These results demonstrate a new background-free imaging modality applicable to a range of inexpensive, readily available and biocompatible silicon particles.

Raman coherence beats from entangled polarization eigenstates in InAs quantum dots

The homodyne-detected transient four-wave-mixing response of InAs/GaAs self-assembled quantum dots shows temporal oscillations of the optically induced Raman coherence arising from two entangled polarization eigenstates of the exciton. The phase sensitive nature of the homodyne detection enables us to follow the time evolution of the nonradiative quantum coherence between the polarization states, providing a measurement of the fine-structure splitting in the dots, which is much less than the inhomogeneous broadening, and the corresponding decoherence rate of the entangled state.

Influence of intervening mismatches on long-range guanine oxidation in DNA duplexes

A systematic investigation of the efficiency of oxidative damage at guanine residues through long-range charge transport was carried out as a function of intervening base mismatches. A series of DNA oligonucleotides were synthesized that incorporate a ruthenium intercalator linked covalently to the 5' terminus of one strand and containing two 5'-GG-3' sites in the complementary strand. Single base mismatches were introduced between the two guanine doublet steps, and the efficiency of transport through the mismatches was determined through measurements of the ratio of oxidative damage at the guanine doublets distal versus proximal to the intercalated ruthenium oxidant. Differing relative extents of guanine oxidation were observed for the different mismatches. The damage ratio of oxidation at the distal versus proximal site for the duplexes containing different mismatches varies in the order GC approximately GG approximately GT approximately GA > AA > CC approximately TT approximately CA approximately CT. For all assemblies, damage found with the Delta-Ru diastereomer was found to be greater than with the Lambda-diastereomer. The extent of distal/proximal guanine oxidation in different mismatch-containing duplexes was compared with the helical stability of the duplexes, electrochemical data for intercalator reduction on different mismatch-containing DNA films, and base-pair lifetimes for oligomers containing the different mismatches derived from 1H NMR measurements of the imino proton exchange rates. While a clear correlation is evident both with helix stability and electrochemical data monitoring reduction of an intercalator through DNA films, damage ratios correlate most closely with base-pair lifetimes. Competitive hole trapping at the mismatch site does not appear to be a key factor governing the efficiency of transport through the mismatch. These results underscore the importance of base dynamics in modulating long-range charge transport through the DNA base-pair stack.

Thermodynamics of Formation of Biological Microemulsion (with Cinnamic Alcohol, Aerosol OT, Tween 20, and Water) and Kinetics of Alkaline Fading of Crystal Violet in Them

The ternary phase diagrams for the formation of biological microemulsions of the combinations CA/AOT/water and CA/Tween 20/water have been presented. The thermodynamics of solution of water in AOT/CA as well as in Tween 20/CA forming w/o microemulsions and solution of oil in Tween 20/water forming o/w microemulsions have been calorimetrically studied. The solution processes are essentially exothermic (with a few exceptions) and have yielded negative entropies, i.e., producing an ordering effect. This has been supported by the measured specific heats of the resulting solution. The pseudo-first-order rate constants (k1) for the alkaline fading of crystal violet in w/o microemulsion medium for the CA/AOT/water and CA/TW 20/water have been found to depend on [water]/[AOT] mole ratio (omega) with maxima at omega = 10. For o/w preparations of CA/TW-20/water, k1 has shown maximum at [CA]/[TW-20] mole ratio omega' = 2, whereas the k2 value has increased with omega'. The salt effect on the reaction has shown significant deviation from expectation in w/o microemulsion. The free energies of activation for the w/o and o/w systems are of the same order, whereas both DeltaHdouble dagger and DeltaSdouble dagger values differ significantly.

Nuclear (DNA, RNA, histone and non-histone protein) and nucleolar changes during growth and senescence of may apple leaves

Quantitative interference microscopy was used to determine changes in nuclear and nucleolar indices (dry mass and cross-sectional area) in upper and lower epidermal cells and adjacent leaf-margin hair cells of the May apple (Podophyllum peltatum L.) leaves over a 42-day period (after leaves emerged above the ground litter). These indices decreased in a highly correlated manner. A ploidy variation may exist between epidermal cells and leaf-margin hair cells. Using the leaf-margin hair cells model, six nuclear macromolecule indices (total nucleic acid, DNA, RNA, total nuclear protein, histone and non-histone protein), nuclear volume, nucleolar volume and perinucleolar volume (measured using quantitative epifluorescence-phase contrast microscopy) all declined with age (42-day study) in a highly correlated manner. The degeneration of the nucleus and nucleolus in the three leaf locations studied followed the patterns observed for programmed cellular senescence and death (necrosis) in epidermal cells of onion leaf bases (stored tissue; leaf bases did not contain chlorophyll) and human epithelial cells (buccal; cervical). We conclude that the epidermal cells and leaf-margin hair cells from green leaves of the May Apple are ideal for the study of programmed cell senescence and death in plants, especially for the partitioning of this process into the study of: the point-of-no-return (solubilization of the karyoskeleton and loss of non-histone proteins and RNA associated with the karyoskeleton from the nucleus); nuclear pycnosis (loss of nuclear dry mass and volume and loss of nuclear internal support structure); chromatin condensation, margination along the inner nuclear envelope; and DNA-histone degeneration; degeneration of the nucleolus and loss of the perinucleolar zone of exclusion. The characterization of chlorenchyma cells during the 42-day period should now be undertaken (leaf senescence as indicated by the beginning of yellowing about 35 days after emergence) to determine whether these cells with functional chloroplasts undergo nuclear changes like those lacking functional chloroplasts.

Nuclear degeneration in epidermal cells of drying onion bulb leaf bases

We tested the null hypothesis 'that activated nuclei and nucleoli in outer-epidermal cells of newly exposed equatorial tissue of the turgid leaf bases of white onions (exposed to the ambient atmosphere by removal of two dry and two turgid leaf bases) remained in that state as the tissue dried' by following nuclear macromolecules (total nucleic acid, DNA, RNA, total protein, histone, and non-histone protein; compared with T0 = 100%) and nucleolar morphologies over a 5-day period. The nuclei became activated within 6 h and remained in that state for 2-3 days [increases in RNA, non-histone protein, and volume of major nucleoli occurred by T12 (about 191, 177, and 289%, respectively) and appearance of the minor nucleoli between T12 and T24 (activation of silent rRNA cistrons)]. Combined nucleolar (major and minor) volumes decreased to 228% by T24 and to 150% by T48. Minor nucleoli were visible at T24 and T48. DNA (DAPI) remained unchanged over that period of time. At the T96 sampling, all nuclear indices had decreased to levels below those obtained at the time of exposure to the ambient atmosphere; minor rRNA cistrons had became silent genes; nuclear volume was about 89% of the original volume; and, nucleolar volume (major nucleoli) was about 93%. The percentages for nuclear indices at T120 were DNA, 85% of T0; RNA, 35%; histone, 87%; non-histone protein, 47%; nuclear volume, 81%; and nucleolar volume, 67%. Of interest is the lack of change in major nucleolar morphologies between T96 and T120 although they decreased in volume during that period. We infer that the karyoskeleton (nuclear matrix) had undergone irreversible degeneration after T48 and that the cells had passed the point-of-no-return in the senescence pathway by T120. We propose that this model for cell senescence and death (drying of turgid leaf bases to form the dry, dead outer covering of the bulbs) simulates post-harvest storage conditions and will prove helpful to those studying cellular senescence mechanisms and associated host-pathogen interactions in plants.

Biological microemulsions V: mutual mixing of oils, amphiphiles and water in ternary and quaternary combinations

The mixing behaviour of plant oils (ricebran, saffola and clove) with water in presence of amphiphiles (Triton X-100, Tween-60, Aerosol OT, Igepal, Na-oleate, ethanol and cinnamic alcohol) in various ternary and quaternary combinations has been studied. The phase behaviour at different mass proportions and temperature has been investigated in the absence and presence of additives such as NaCl, glucose, urea and cholesterol. Of all the combinations studied, those with ethanol plus sodium oleate as amphiphile have shown maximum extent of single phase microemulsion formation. The presence of urea in the aqueous medium has further increased the monophasic extent whereas NaCl has decreased it. Cholesterol in oil and glucose in water have apparently shown inert effects. The effects of the additives on the formation of biphasic or triphasic formulations, on the other hand, have been found to be distinct and well-dependent on [H2O]/[amphiphile] mole ratio and temperature. Spectral measurements of I3- in the aqueous micropool in microemulsion of clove oil/(ethanol + Na-oleate)/water have shown the microenvironment to be physicochemically different from bulk water.

Myocardial perfusion in new-onset angina patients with single vessel disease

The aim of this study was to investigate myocardial perfusion of the left ventricle during stress (exercise scintigraphy with thallium-201) in 25 patients having new-onset angina (NA) with single-vessel disease. In 14 cases (56%) the lumen of the vessel was obstructed by more than 75% and in 6 cases (24%) it was totally occluded. Angiographically visible collaterals to the occluded arteries from other vessels were present in all these cases. All of the patients studied had some form of myocardial perfusion disturbance. In 13 patients (52%) perfusion defects were limited to distribution within the obstructed artery; the other 9 patients (36%) had defects in the pool of the intact artery with or without defects in the pool of the obstructed artery. In the 4 patients (44.4%) having a totally occluded artery, perfusion defects were observed only in the pool of the intact artery supplying the collaterals, while in 5 patients (55.6%) perfusion defects were found both in the pool of the intact artery supplying the collaterals as well as in the obstructed vessel. We conclude that in patients with NA, stress dependent perfusion defects are present not only in the pool of the obstructed artery but also in the intact artery supplying the collaterals. This point to the possible presence of 'steal' syndrome in these patients.

Biological microemulsions: Part IV--Phase behaviour and dynamics of microemulsions prepared with vegetable oils mixed with aerosol-OT, cinnamic alcohol and water

Microemulsification of vegetable oils (ricebran, saffola, soyabean, sesame, palm and linseed) with water using aerosol-OT and cinnamic alcohol as mixed amphiphiles was studied. The biological microemulsions formed covered on the average approximately 27% of single phase area in the triangular phase diagram. The multiphasic zone for saffola was studied in detail, two- and three-phase zones were identified with patches of thick gel. The effect of temperature on the multiphase formation in the range 29-55 degrees C was also studied. The formation of multiphase and their proportions found to depend on the type of oil. The biological microemulsions at reasonable water/AOT mole ratio showed moderate increase in conductance with temperature. The viscosity of the microemulsions was high. Of the studied systems (sesame, saffola and ricebran) the viscosity of the first two decreased with the rate of shear whereas that of ricebran increased. When cinnamic alcohol was used as the oil, the trend of viscosity was similar to that of sesame and saffola.

Changes in nuclear macromolecules and nucleolar volume associated with selective ribosomal cistron activation by ethylene

Pieces of leaf base tissue from the equatorial region of the third turgid onion (Allium cepa L.; yellow, sweet Spanish, quiescent tissue) leaf base with two visible major nucleoli (volume = 0.51 microns3) and two inactive minor nucleolar organizer regions (NORs) in the outer epidermal cells were placed in shallow water (time = T0 control). After 3 h (T3 control), the two visible nucleoli enlarged (178% of T0) and changed shape (from 88% round and 12% oval at T0 to 5% round, 68% oval, 20% elongated-oval, and 7% dumbbell). The minor NORs remained inactive. Nuclear RNA and non-histone protein (nHP) increased (RNA = 128% and nHP = 134%, compared with T0 data, set at 100%). The content of DNA and histone protein (H) in nuclei remained unchanged. Major nucleoli in pieces of onion placed in 10(-5) M ethylene enlarged and minor nucleoli became visible in 33% of the nuclei; i.e., ethylene acted as a selective ribosomal cistron regulator. The nucleolar volume (212% of T0) was statistically greater than those for T0 and T3. DNA and H remained unchanged (not statistically different) but RNA (159% of T0) and nHP (169% of T0) were greater (statistically significant) than those for T0 and T3 controls. Cobalt chloride (10(-5) M Co) alone or in 10(-5) M ethylene (Co + E) inhibited the enlargement of some of the major nucleoli and completely inhibited the appearance of minor nucleoli. The nucleolar volumes for the cobalt and for cobalt-ethylene treatments were significantly less than those for T3 controls and ethylene treatment at T3. DNA and histone did not change.(ABSTRACT TRUNCATED AT 250 WORDS)

Experimental visceral leishmaniasis: role of trans-aconitic acid in combined chemotherapy

We previously reported the effectiveness of trans-aconitic acid (TAA) as an antileishmanial compound. Inhibitory effects of TAA along with other antileishmanial compounds on transformation and in vitro multiplication in macrophage cultures of Leishmania donovani have been assessed. The efficacy of TAA in combined chemotherapy of experimental visceral leishmaniasis has also been evaluated along with those of commonly used antileishmanial compounds such as sodium stibogluconate, pentamidine, and allopurinol. TAA (2 mM) inhibited transformation of L. donovani amastigotes to promastigotes by 95.2%, whereas in combination with pentamidine (5 micrograms/ml), allopurinol (10 micrograms/ml), and sodium stibogluconate (50 micrograms of Sb per ml), it inhibited transformation by about 100, 99, and 98.5%, respectively. Sodium stibogluconate (20 micrograms of Sb per ml), pentamidine (2 micrograms/ml), and allopurinol (5 micrograms/ml) suppressed the amastigote burden in peritoneal macrophage cultures from BALB/c mice by 32.6, 56.1, and 46.3%, respectively. When these three drugs were used along with TAA (5 mM), the parasite loads were reduced by 100, 100, and 88.1%, respectively. TAA (5 mM) alone suppressed the amastigote burden by 59.5%. In experimental visceral leishmaniasis in hamsters (1-month model), TAA at a dose of 200 mg/kg of body weight per day suppressed the spleen parasite load by 73.5%, and TAA in combination with sodium stibogluconate (50 mg of Sb per kg per day), pentamidine (8 mg/kg/day), and allopurinol (15 mg/kg/day) inhibited the spleen parasite load by 98, 98.9, and 97%, respectively. Individually, these three drugs inhibited the parasite load by 35, 20, and 22%, respectively. TAA (400 mg/kg/day) inhibited the spleen parasite load by 99.8%, but an inhibitory effect of approximately 100% was noted when TAA was supplemented with an antileishmanial drug. TAA was administered in experimental animals through oral, intraperitoneal, and intramuscular routes; the intramuscular route was most effective.

Perinatal mortality in caesarean section: a disturbing picture of unfulfilled expectations

Indications for caesarean section had been studied in a 2-year period and the incidences were compared to that of the same 15 years back. Though there are more incidences of caesarean section, still perinatal death is a major concern to all. The study included a total of 291 perinatal deaths of which there were 208 early neonatal deaths and 83 stillbirths over a period of 2 years from January, 1990 to December, 1991. Caesarean section is being increasingly performed for foetal interest, but this study reveals that perinatal mortality is still high though cesarean section rate has increased in recent times.

Clinical course and left ventricular function in patients with acute myocardial infarction following delayed recanalization of infarct-related artery

The effect of delayed recanalisation of the infarct related artery on clinical course and left ventricular functions was studied in 23 patients with acute myocardial infarction (Group 2). Another 82 patients with acute myocardial infarction served as controls: 48 patients with immediate recanalisation of the infarct related artery following intracoronary thrombolytic therapy (Group 1) and 34 patients with unsuccessful thrombolysis with the artery remaining occluded on repeat angiography (Group 3). Baseline clinical characteristics and left ventricular ejection fractions in the three groups did not differ statistically. Following intracoronary thrombolysis the clinical features and left ventricular functions in the three groups, respectively were as follows: post infarction angina--45.8%, 13.1% and 11.8% (1 vs. 2 and 3, P < 0.05); reinfarction--29.2%, 8.7% and 11.8% (1 vs. 2 and 3, P < 0.05); mortality--0%, 0% and 11.8% (1 and 2 vs. 3; P < 0.05); aneurysm--16.7%, 21.7% and 52.9% (1 and 2 vs. 3, P < 0.05); heart failure--20.8%, 21.7% and 47.1% (1 and 2 vs. 3, P < 0.05). Left ventricular ejection fractions on the second and on days 10-14 were, respectively, 47.6 +/- 1.1%, 42.8 +/- 1.1% and 39.2 +/- 1.6% (1 vs. 2 and 3, P < 0.05) and --52.1 +/- 1.0%, 48.9 +/- 1.1% and 44.3 +/- 1.5% (1 and 2 vs. 3, P < 0.05). Thus following delayed recanalisation of the infarct related artery the clinical course and left ventricular function improved significantly in comparison to patients without recanalisation.

Temperature invariance of quantum well modulators using a feedback circuit based on the quantum confined Stark effect

We report the design and performance characteristics of a voltage feedback circuit which can rapidly compensate for the temperature-dependent shift of the excitonic peak energy positions in quantum confined Stark effect modulators. The energy position remains invariant over a temperature shift of 10 degrees . The circuit is simple and can be operated with a single device or an array of modulators.

Evaluation of antileishmanial activity of trans-aconitic acid

TAA, an inhibitor of the enzyme aconitase, inhibits the growth of L. donovani promastigotes. Morphogenic transformation of the amastigote to the promastigote (table; see text) form in vitro was also inhibited by 2 mM TAA. TAA also reduced multiplication of the parasite in macrophage culture. In the hamster model of leishmania, TAA significantly reduced the parasitic burden of liver. In acute toxicity tests with BALB/c mice no deaths were recorded even at a dose level of 2 g/kg body wt/day.

High-resolution nonlinear laser spectroscopy of room-temperature GaAs quantum-well structures: observation of interference effects

We describe frequency-domain four-wave mixing spectroscopy measurements near the fundamental band edge in room-temperature GaAs multiple quantum wells. The line-shape information gives a measure of the dynamical behavior of the material and what is to our knowledge the first observation of an interference line shape due to a dominant slow contribution to the nonlinear response.

Thermodynamics of water-induced precipitation of cholesterol and its acetate, benzoate and stearate derivatives dissolved in 1,4-dioxane and 2-propanol

The energetics of the precipitation process depended on the solute-solvent combination and the enthalpy and entropy of precipitation compensated each other. The partial molal volumes of the lipids in both the solvents were greater than the anhydrous molar volumes, except for cholesterol in 1,4-dioxane and cholesteryl acetate in 2-propanol where the order was reverse. While the partial molal compressibilities of all the solutes studied were negative in 1,4-dioxane, those of cholesterol and cholesteryl acetate in 2-propanol were, respectively, negative and positive. The negative values were supported by considerable solvation of the solutes, particularly in 1,4-dioxane.

Water-induced precipitation of cholesterol dissolved in organic solvents in the absence and presence of surfactants and salts

The precipitation of cholesterol dissolved in organic solvents, viz. methanol, ethanol, n-propanol, isopropanol, acetone and 1,4-dioxane, by the addition of water has been studied. The effects of the solvents towards the precipitation follow the order: methanol greater than ethanol greater than acetone greater than dioxane greater than n-propanol greater than iso-propanol, the solvent dioxane however exhibits a change in the order at higher concentration. Additives like Triton X-100, sodium cholate, sodium deoxycholate, sodium dehydro cholate, sodium salicylate and sodium chloride have some protective action against precipitation, the maximum protection being that of Triton X-100. The additives have shown better protective action in propanols and dioxane than in methanol, ethanol and acetone. Analysis of solvent composition and dielectric constant has revealed specific solvent effects on the water-induced precipitation of cholesterol. Thermodynamic analysis of the precipitation phenomenon and the unique role of solvent structure on cholesterol precipitation has been discussed.

Model biological microemulsions: Part I--Phase behaviour and physicochemical properties of cholesteryl benzoate and sodium deoxycholate contained microemulsions

Phase behaviour and some physicochemical properties of cholesteryl benzoate-contained microemulsions of xylene and heptane with water using sodium deoxycholate and butan-1-ol as surfactant and co-surfactant respectively have been studied. While the microemulsion area of xylene depends insignificantly on the surfactant/co-surfactant ratio, that of heptane shows appreciable dependence. At surfactant + co-surfactant percentage of 50 or above, both the systems become oil continuous. With respect to time and temperature, the microemulsion systems have been found to be very stable. At low percentage of water, the xylene system is considerably viscous; that of heptane is less viscous but shows viscosity maximum at 45% water. Cholesterol in xylene has given greater viscosity than cholesteryl benzoate. The equivalent conductance of both the systems increase with increasing water content and the values are comparable. Unlike normal electrolyte solutions, the products of equivalent conductance and viscosity (the Walden product) sharply rise with increased water content, which suggests a special mechanism of conduction via 'channel' formation. The overall rigidity of the microemulsions is suggested by their lower specific volumes and compressibilities at all compositions. The excess specific volumes and excess compressibilities at different percentages of water are presented.