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Biomedical subjects

M K Basu

Publications and source records attributed to M K Basu.

At least 91 records · Page 5Linked to original sources
PubMed1977

Surface properties of membrane systems. Transport of staphylococcal delta-toxin from aqueous to membrane phase.

Hemolytic delta-toxin from Staphylococcus aureus was soluble in either water, methanol or chloroform/methanol (2 : 1, v/v). The toxin spread readily from distilled water into films with pressures (pi) of 10 dynes/cm on water and 30 dynes/cm on 6 M urea; from chloroform/methanol it produced 40 dynes/cm pressure on distilled water. The toxin adsorbed barely from water (pi = 1 dyne/ cm) but it did rapidly from 6 M urea (pi = 35 dynes/cm). The protein films had unusually high surface potentials, which increased with the film pressure and decreased with increasing both pH and urea concentration in the aqueous phase. The fluorescence of 1-aniline 8-naphthalene sulfonate with delta-toxin was much greater than that with RNAase and dipalmitoyl phosphatidylcholine itself, indicating probably a marked lipid-binding character of the toxin. By circular dichroism the alpha-helix content of delta-toxin was 42% in water, 45% in methanol, 24% in 6 M urea. Infrared spectroscopy showed predominant alpha-helix in both 2H2O and deuterated chloroform/methanol as well as in films spread from either solvent on 2H2O. In spreading from 6 M [2H]urea, in which the major infrared absorption was that of [2H]urea with peaks at 1600 and 1480 cm(-1), the delta-toxin film showed prevalently non-alpha-helix structures with major peak intensities at 1633 cm(-1) > 1680 cm(-1), indicating the appearance of new beta-aggregated and beta-antiparallel pleated sheet structures in the film. The data prove that (1) high pressure protein films can consist of alpha-helix as well as non-alpha-helix structures and, differently from another cytolytic protein, melittin, delta-toxin does not resume the alpha-helix conformation in going into the film phase from the extended chain in 6 M urea; (2) conformational changes are important in the transport of proteins from aqueous to lipid or membrane phase; (3) delta-toxin is by far more versatile in structural dynamics and more surface active than alpha-toxin.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1977

Effects of prostaglandins E2 and F2alpha on lecithin biosynthesis by cultured lung cells.

Transformed cells from human lung carcinoma (Line A549), resembling type II pneumocytes, were cultured in monolayer at 37 degrees C and incubated for five hours with 3H-choline and 14C-palmitate in the presence of various concentrations of prostaglandins (PGS) E2 and F2alpha. In the control (no PG) the level of % palmitate incorporation was 13.5 x as high as that of choline, after taking isotope dilution into account. Between the concentrations studied, 0.1 and 10 muM, both prostaglandins stimulated markedly the incorporation of both precursors, though choline up to 3 x better than palmitate. This was indicated by a change in the palmitate/choline incorporation ratio from 13.5 to as low as 4.2. At the lowest PG concentration, 0.1 muM, PGE2 was much more effective than PGF2alpha in stimulating the incorporation of both precursors.

Cell Line↗
PubMed1976

Jejunal mucosal abnormalities in patients with recurrent aphthous ulceration.

Jejunal biopsies in 33 patients with troublesome recurrent aphthous ulceration seen over one year showed eight with flat mucosa compatible with coeliac disease. All remitted completely on a gluten-free diet, both clinically and haematologically, and the aphthous ulceration did not recur. Gluten sensitivity is aetiologically important in patients with recurrent aphthous ulceration and flat mucosa, and patients with recurrent ulceration should undergo jejunal biopsy.

Adolescent↗
PubMed1976

pH, temperature, humidity and the dynamic force-area curve of dipalmitoyl lecithin.

Both high pH at 25 degrees C and humidity at 37 degrees C prevent DPL films from attaining zero surface tension, whereas humidity at 25 degrees C and high pH at 37 degrees C do not. At 37 degrees C DPL lowered surface tension to zero when spread from organic solvent or when absorbed from aqueous 0.15 M NaCl in the surface balance in which the surface film was exposed to the room air (dry film). Upon saturation of the atmosphere with water vapor in equilibrium with the aqueous phase at 37 degrees C in a closed chamber, DPL lost the ability to produce zero surface tension, and the gamma min of the DPL film increased from zero to 22 dyne/cm. Addition of DPL in chloroform to distilled water before dispersion by sonication did not prevent the effect of the humidity. However, when the chloroform solution of DPL was added to 0.15 M NaCl before sonication, the adsorbed film produced immediately a stable gamma min of zero in a saturated atmosphere, 37 degrees C. In the absence of chloroform, with DPL adsorbed from either distilled water or 0.15 M NaCl, the effect of humidity was reversed either by removing the chamber and returning the wet film to room air or by introducing small quantities of dispersing agents such as cholesteryl palmitate. However, whereas the effect of humidifying the air was reversible indefinitely, the effect of cholesteryl palmitate (zero surface tension, wet or dry film) was irreversible. This means that there are substances or conditions that can assist DPL films in maintaining zero surface tension when such films are exposed to humidity-saturated air at 37 degrees C.

Humidity↗
PubMed1975

Studies on the binding of 1-anilino-8-naphthalene sulfonate to very low density and high density himan serum lipoproteins.

Very low density and high density lipoproteins have been isolated from human plasma and their interaction with 1-anilin0-8-naphthalene sulfonate has been studied under different conditions of pH and added salt. Intrinsic fluorescence of bound 1-anilino-8-naphthalene sulfonate was higher for high density lipoproteins then for very low density lipoproteins, but was unaffected by salt in both systems. Binding of 1-anilino-8-naphthalene sulfonate by both these lipoproteins was saturable and was higher in the presence of added NaCl or CaCl2, Ca2+ having a greater effect than Na+ in enhancing fluorescence. The binding data were analyzed by Scatchard plots; the number of binding sites and the affinity of 1-anilino-8-naphthalene sulfonate for the site increased with increasing salt concentration. Fluorescence pH curves were similar to those published for phospholipids. From these and previous observations it is suggested that the phospholipids probably represent the major binding sites for 1-anilino-8-naphthalene sulfonate.

Anilino Naphthalenesulfonates↗
PubMedDate not supplied

Targeting of liposomal andrographolide to L. donovani-infected macrophages in vivo.

Despite the rapid development in medicinal and pharmaceutical technology, the targeting of drugs to phagocytic cells in macrophage-related diseases still remains a major unsolved problem. By using the mannosyl-fucosyl receptors on macrophages, attempts were made to target antileishmanial drugs encapsulated in mannosylated or fucosylated liposomes to treat experimental leishmaniasis in the hamster model. Mannosylated liposomes were found to be more potent in delivering antileishmanial drugs to phagocytic cells. Liposomes loaded with an indigenous drug, andrographolide, a labdane diterpenoid isolated from Indian medicinal plant Andrographis paniculata, were prepared and tested against experimental leishmaniasis in a hamster model. Mannosylated liposomes loaded with the drug were found to be most potent in reducing the parasitic burden in the spleen as well as in reducing the hepatic and renal toxicity. In addition, mannosylated drug-loaded liposome-treated animals showed a normal blood picture and splenic tissue histoarchitecture when compared with those treated with free drug or regular liposomal drug. Such a drug-vehicle formulation may be considered for clinical trials.

Animals↗
PubMedDate not supplied

Bacopasaponin C: critical evaluation of anti-leishmanial properties in various delivery modes.

Bacopasaponin C, an indigenous glycoside, was isolated from Indian medicinal plant Bacopa monniera (b. brahmi) and was tested for antileishmanial properties both in free and in various delivery modes, e.g., niosomes, microspheres, and nanoparticles that are used now as alternatives to more commonly used liposomes. The different vesicles were prepared by published protocols. The percent intercalation of Bacopasaponin C in liposomes, niosomes, and micropspheres determined at its absorption maximal (lambda(max) = 238 nm, epsilon = 8.6 x 10(3) M(-1) x cm(-1)) was found to be 30; for nanoparticles it was 50. At equivalent dose of 1.75 mg/kg body weight, every third day for a total of 6 doses in 15 days, Bacopasaponin C in all the vesicular forms was found to be very active. An inverse linear relationship between the efficacy and the size of the vesicles was established. As analyzed from tissue histology, blood pathology, and specific tests related to normal liver and kidney functions, Bacopasaponin C in each of the four vesicular forms was found to be without any side effects. Thus, because of its indigenous origin and non-toxic nature, Bacopasaponin C could very well be considered for application in the clinic through these alternative delivery modes.

Animals↗
PubMedDate not supplied

Designing and testing of an effective oil-in-water microemulsion drug delivery system for in vivo application.

The phase behavior of a new psedoternary system of clove oil/Tween 20 has been studied. Several compositions from the single-phase region were selected and their stability toward time, temperature, and electrolytes has been examined. A particular composition(clove oil/Tween 20/water as 5/30/65) was chosen as the drug delivery system from the clear oil-in-water zone of the pseudoternary system. The droplet dimension and the polydispersity state of the particular composition was determined by dynamic light scattering. A bioactive compound quarcetin was encapsulated in the vehicle. The efficacy of the drug in the vehicle was examined against leishmaniasis in hamster models. The hepatotoxicity of the vehicle (o/w microemulsion) with and without the drug quarcetin was examined by estimating serum alkaline phosphatase, glutamate pyruvate transaminase, urea, and creatinine.

Animals↗