Unequal lives: a sociodemographic analysis of COVID-19 transmission and mortality in India.

OBJECTIVES: Existing socio-economic inequalities shape, in very particular and measurable ways, the differential impact that a disease has on different sections of the same society. This is particularly true of COVID-19, which has rapidly exhausted the public health system in India, and magnified the gradient of vulnerability in an underserved populace. Using publicly available data, we have aimed to deconstruct this gradient into individual variables of inequality and quantify their impact on the transmission and mortality outcomes of COVID-19 in India. STUDY DESIGN: Sociodemographic analysis. METHODS: We quantify doubling times and case fatality ratios for all districts in India, then correlate them to 20 variables of socio-economic vulnerability and demographic structure. Variables that exhibit persistent correlation are then analysed using multivariate beta regression models to validate their impact on COVID-19 outcomes in India. RESULTS: The transmission of COVID-19 in India is enhanced by the lack of access to indoor latrines, drainage facilities, electricity, and proximate sources of drinking water. Transmission is slowed by the presence of an elderly population. Fatality rates relate negatively to an area's medical infrastructure and the presence of a college-educated populace. CONCLUSIONS: An interactive matrix of social inequalities, cultural practices, and behavioural patterns determines the path of COVID-19 through a community. Specific variables exhibit patterns of persistent vulnerability; others indicate a resistance to infection and mortality. This body of evidence, when incorporated into policy design, may lead to localised, need-sensitive models of intervention, both for preventive measures and medical care.

Association between components of metabolic syndrome and prostatic enlargement: An Indian perspective.

BACKGROUND: To find association between prostate gland volume to components of the metabolic syndrome. METHODS: Cross-sectional, observational study in a tertiary care hospital of the Armed Forces of India. A total of 115 male patients aged 50-65 years attending the Urology OPD between Jan 2014 and July 2015 with lower urinary tract symptoms (LUTS) were included. Men with known malignant disease including carcinoma prostate, those on medical management for BPH and individuals with previous history of surgery related to urinary bladder/prostate were excluded. Blood Pressure (BP), weight in kgs, height, waist and hip circumference to nearest cm were recorded. Body Mass Index (BMI) and Waist/Hip ratio (WHR) were calculated. Fresh serum was analysed for lipid profile and glycaemic levels. The International Diabetes Federation (IDF) - 2005 guideline for metabolic syndrome was used for the diagnosis. The total prostate volume and the severity of LUTS as per AUA Symptom index were considered as the primary and secondary outcome measure respectively. Statistical software SPSS version 20 was used for analysis. Mean prostate volume was compared with the components of MetS. An alpha level of 5% was considered significant. RESULTS: The study showed positive association between prostate volume with metabolic syndrome and its four components - raised blood pressure, fasting blood glucose and triglycerides and HDL ≤ 40 mg/dl. No correlation was found with waist circumference. CONCLUSION: Our study indicates that metabolic syndrome and its individual components may predispose patients to a higher risk of prostatic enlargement/LUTS.

Synthesis and characterization of Cu/Ag nanoparticle loaded mullite nanocomposite system: A potential candidate for antimicrobial and therapeutic applications.

BACKGROUND: Microbial resistance to antibiotics has triggered the development of nanoscale materials as an alternative strategy. To stabilize these particles an inert support is needed. METHOD: Porous nanomullite developed by sol-gel route is loaded with copper and silver nanoparticle by simple adsorption method. These nanocomposites are characterized using XRD, FTIR, TEM, SEM, EDAX and UV-visible spectrophotometer. Antibacterial activity of these nanocomposites against Gram positive and Gram negative bacteria are performed by bactericidal kinetics, flow cytometry and MTT assay. The underlying mechanisms behind the antimicrobial property and cell death are also investigated by EPR spectroscopy, intracellular ROS measurement and ß-galactosidase assay. The cytocompatibility of the nanocomposites is investigated by cell viability (MTT), proliferation (Alamar blue) and wound healing assay of mammalian fibroblast cell line. RESULTS: Nanocomposites show a fairly uniform distribution of metal nanoparticle within mullite matrix. They show excellent antibacterial activity. Metal ions/nanoparticle is found to be released from the materials (CM and SM). Treated cells manifested high intracellular oxidative stress and ß-galactosidase activity in the growth medium. The effect of nanocomposites on mammalian cell line depends on exposure time and concentration. The scratch assay shows normal cell migration with respect to control. CONCLUSION: The fabricated nanoparticles possess diverse antimicrobial mechanism and exhibit good cytocompatibility along with wound healing characteristics in mouse fibroblast cell line (L929). GENERAL SIGNIFICANCE: The newly synthesized materials are promising candidates for the development of antimicrobial ceramic coatings for biomedical devices and therapeutic applications.

Male Andropause : A Myth or Reality.

Male andropause, male climacteric or viropause is a condition in which men suffer from complex symptomatology due to low androgen level with aging. After the age of 40 years testosterone level starts declining and andropause corresponds to the age at which a pathogenic threshold is reached. This review summarizes the etiology, consequences, screening, diagnosis, monitoring of androgen deficiency in aging male (ADAM). The pros and cons of testosterone replacement therapy (TRT) in elderly male have been discussed. Currently oral, transdermal, transbuccal, intramuscular, and subcutaneous implants are available for clinical use. The choice is made by physicians based on therapeutic indication and patient preferences.

Post caesarean vesicouterine fistulae-- Youssef syndrome: our experience and review of published work.

OBJECTIVE: To analyse the incidence, symptomatology, diagnosis and therapeutic aspects of Youssef syndrome (post caesarean vesicouterine fistula), and to review relevant published work. METHODS: A retrospective study from the urosurgical unit of a tertiary care referral hospital was carried out. In a retrospective analysis of urogenital fistulae over 10 years, we identified 14 patients with uterovesical fistulae, resulting from caesarean section. All the patients were evaluated by history, physical examination, radiological tests and cystoscopy. All patients underwent transperitoneal repair of these fistulae with omental interposition. Results of surgery were evaluated by absence of cyclic haematuria, stoppage of urinary incontinence, and achievement of fertility. RESULTS: A total of 12 patients who had minimum follow up was included in the present study. The results showed that 50% of the fistulae resulted from emergency caesarean operation with 58% of patients presenting after their second caesarean section. The mean age of the patients was 19 years (range 15-29) and mean duration of symptoms was 7 months (range 3-16). Menouria and amenorrhoea were predominant presenting symptoms. The results of surgical treatment were excellent with good continence and resolution of the cyclic haematuria. Three pregnancies (37.5%) which resulted in elective caesarean section were recorded. CONCLUSION: Vesicouterine fistulae, despite being infrequent, are no longer a rare diagnosis and are most commonly secondary to lower segment caesarean section. With patient history and selected investigations diagnosis is relatively easy. The surgical repair of these fistulae is standard treatment, especially with delayed fistulae with achievement of total continence, and complete resolution of cyclic haematuria. Meticulous practice of obstetric and surgical principles during caesarean section can prevent the formation of these fistulae.

A fluorescence anisotropy study of stabilizing effect of tri- and tetra- nitrovasodilatory drugs on DPPC liposomal membrane.

Glyceryl trinitrate (GT) and pentaerythritol tetranitrate (PT) are two vasodilatory drugs. The physical properties of the membrane lipid matrix, which determine the structure and function of the membrane-bound proteins, generally control the perturbation mechanism of these drugs. Thus, physical interaction of these drugs with membrane lipids is very crucial for their clinical use, different cellular processes, as well as for targetted drug delivery systems. In the present paper, we have reported for the first time the interaction between these drugs and the lipid molecules in the liposomal system of dipalmitoylphosphatidyl-choline (DPPC), as measured by steady-state fluorescence anisotropy using 1,6-diphenyl-1,3,5-hexatriene (DPH) as fluorescent probe. Our results show that by dissolving in the lipid matrix these two drugs effectively stabilise the liposomal membrane: the effect being more in case of GT than in PT, indicating that the rigidifying effect is independent of the number of nitrate groups of the two drugs. This effect increases with the increase in drug concentration, implying solubilisation of all drug molecules. Though our in vitro study has more physical significance than a physiological one, the results obtained here may be used to interpret the effects that are observed in vivo.

Physicochemical basis of the universal genetic codes--quantitative analysis.

Quantitative mathematic models have been developed to correlate the fragment hydrophobicity contribution constants (faa) of 20 amino acids with the physicochemical properties (mu, Hb, and square root of MW) of the four bases (U, A, C, G) of the codons, or those of the anticodons. Using the general equation faa = a mu 1 + b mu 2 + c mu 3 + d square root of MW1 + e square root of MW2 + f square root of MW3 + g Hb1 + h Hb2 + i Hb3 + j, where 1, 2, 3 refer to the first, the second and the third base respectively, correlation coefficient of about 0.82 can be obtained for all 20 amino acids coded by 61 different triplet codes. These correlations are statistically highly significant, even though they do not take into account the involvement of various factors and peptidyl transferases. Furthermore, the reasons for the three stop codons are revealed. The graphic presentation of the codons and the amino acids coded separates the acidic and the basic, the aromatic and the heterocyclic amino acids into different quadrants of an octagon. This is in agreement with the ancient Chinese Ying-Yang theory embedded in the classical I-Ching.

Role of merocyanine dye as a proton pump in photovoltage generation.

A novel photoelectrochemical cell using a proton pump mechanism in the aggregated planar structure of oxidised cholesterol incorporating merocyanine dyes is reported. Lipid dye binding, as verified from spectral studies and photoisomerisation of the dye, is responsible for this photovoltage generation whose magnitude and storage duration are related to the equilibrium constant of dye-lipid binding through an empirical formula.

Liposome formation of egg lecithin and its interaction with iodine.

The sonicated dispersion of egg lecithin (phosphatidylcholine) in water forms 1:1 molecular complex with iodine, when its concentration is above 1.6 X 10(-5) M. The thermodynamic and spectrophotometric properties of this complex have been determined. The thermodynamic values are: K (25 degrees C) = 1.6 X 10(3) 1 X mol-1, delta G degrees = -18.4 KJ X mol-1, delta H degrees = -27.4 KJ X mol-1 and delta S degrees = -30.0 J X mol-1 X deg-1. The complex shows two absorption bands: one at 293 nm, which is the charge transfer band and the other at 370 nm, which is the blue shifted visible iodine band at 460 nm in water.

Inhibition of ribonucleotide reductase by a new class of isoindole derivatives: drug synergism with cytarabine (Ara-C) and induction of cellular apoptosis.

The hydroxyisoindole dione derivatives ISID and MISID are new compounds with structures resembling purines and possessing a hydroxamic acid moiety which is the pharmacophore of hydroxyurea (HU), an inhibitor of ribonucleotide reductase (RR). ISID and MISID exhibited 100- to 500-fold higher cytotoxicity as compared to HU against cell lines sensitive (CEM/0) or resistant to ara-C (CEM/ara-C/7A; CEM/dCk[-]). Both MISID and ISID showed significant inhibitory activity of ribonucleotide reductase (RR). Treatment of CEM/0 cells with 10 microM ISID showed a linear decrease in all the dNTPs leading to a complete depletion by 4 hours with no recovery of enzymatic activity of RR up to 48 hours in the presence of the drug, suggesting an irreversible inhibition of this enzyme. However, 10 microM MISID caused a significant time dependent, but reversible inhibition of RR in a whole cell assay in CEM/0 cells. Pretreatment of CEM/0 cells with 10 microM MISID for 1 hour increased cellular ara-CTP concentrations approximately 2-fold as compared to untreated controls. However, a reduction in intracellular ara-CTP concentration was observed following a commensurate depletion of ATP in these cells after 4 hrs of ISID pretreatment. Similarly, the ara-CTP concentration was augmented by 1.6-fold following pretreatment of CEM/0 cells with 10 microM MISID for 4 hours. Significant apoptotic cell death was detected in CEM/0 cells treated with ara-C, ISID or MISID alone or in combination. Ara-C treatment induced HMW (high molecular weight) DNA fragmentation at earlier times which subsequently led to oligonucleosomal DNA fragmentation by 48 hrs. The sequential treatment of CEM/0 cells with MISID followed by ara-C resulted in increased DNA fragmentation in the 2.0 to 4.0 Kb range in comparison to those cells treated with either ara-C or MISID alone. The increased apoptotic cell death explained the synergistic cytotoxicity of the combination of ara-C and MISID against CEM/0 cells observed earlier. We conclude that the inhibition of RR by these agents induces leukemic cell apoptosis, a mechanism which is further potentiated when these RR inhibitors are combined with ara-C. Since new compounds do not require activation, as do other clinically useful RR inhibitors, further studies for their potential use against leukemias and solid tumors are warranted.

The synergism of 6-mercaptopurine plus cytosine arabinoside followed by PEG-asparaginase in human leukemia cell lines (CCRF/CEM/0 and (CCRF/CEM/ara-C/7A) is due to increased cellular apoptosis.

BACKGROUND: The only effective drug against ALL that inhibits protein synthesis is Asparaginase (ASNase). The drug depletes asparagine (Asn) in serum and cells and since the leukemic T-cells (thymic origin cells) lack asparagine synthetase, the amino acid starvation leads to apoptosis. When PEG-ASNase is combined with antimetabolite drugs such as ara-C, or combinations of 6-MP followed by ara-C, it augments the cytotoxic effect synergistically against human T-leukemia cells. MATERIALS AND METHODS: Synergism studies with two- or three-drug combination regimens in the human leukemia cell lines, CEM/0 and CEM/ara-C/7A have been investigated along with its effect in inducing apoptosis. RESULTS: The IC50 (approximately Dm) values of ara-C were 0.032 microM and 0.11 microM, and that of PEG-ASNase were 0.002 IU/ml and 1.52 IU/ml against CEM/0 and CEM/ara-C/7A cells, respectively. Thus, CEM/ara-C/7A cell line that is partially resistant to ara-C exhibited 681-fold cross-resistant to PEG-ASNase as compared to CEM/0. The concurrent drug exposure of ara-C and PEG-ASNase for 48 hours resulted in IC50 values of 0.56 nM for ara-C and 0.56 mIU/ml for PEG-ASNase respectively, in CEM/0 cells which represents a 57.4-fold synergism compared to ara-C alone. In the CEM/ara-C/7A cell line, the co-incubation with these two drugs resulted in IC50 value of 0.015 microM for ara-C and 0.015 IU/ml for PEG-ASNase respectively, or a 7.25-fold synergism as compared to ara-C and 101.1-fold synergism in comparison with PEG-ASNase alone. Pre-clinical studies involving three-drug combination consisting of 6-MP, ara-C and PEG-ASNase in a sequence-specific manner showed a 15.6-fold synergism against CEM/0 cell line over the two-drug combination of 6-MP followed by ara-C or approximately 160-fold syneryism over ara-C alone. CONCLUSION: The two-drug combination of ara-C and PEG-ASNase or the three-drug combination of 6-MP, ara-C and PEG-ASNase in the ara-C sensitive and resistant cell line showed significant drug synergism and CEM/ara-C/7A cells exhibited collateral sensitivity to PEG-ASNase. The three-drug combination also induced dose-dependent apoptotic DNA fragmentation which was higher than the two-drug combination of 6-MP and ara-C. We also conclude that the sequence specific use of PEG-ASNase in combination with the nucleoside analog drugs may benefit leukemia patients in early relapse.

Increased p21/WAF-1 and p53 protein levels following sequential three drug combination regimen of fludarabine, cytarabine and docetaxel induces apoptosis in human leukemia cells.

Combinations of nucleoside analog drugs, such as F-araA and ara-C, combined with Topoisomerase II inhibitors, such as anthracyclines, are synergistic against human leukemic T-cells and induce apoptotic cell death. Similarly, nucleoside analog drugs followed by mitotic inhibitors also have a synergistic effect. Sequence specific combinations of F-araA followed by ara-C and Taxotere (docetaxel) in CEM/0 cells showed a 2- to 3-fold synergism over the two drug (F-araA + ara-C) combinations and 2- to 4-fold synergism over Taxotere alone. This synergism was evident due to enhanced cellular apoptosis. In the CEM/ara-C/7A cell line, which is partially resistant to ara-C, the synergy observed with the triple drug combination was 9-fold greater than the F-araA plus araC combination, and 3-fold greater than Taxotere alone, making this three-drug regimen collaterally sensitive to ara-C. This study describes the mechanisms of the synergistic effect in regards to apoptosis achieved by three-drug regimens comprised of two nucleoside analog drugs and a mitotic inhibitor in comparison with the combination of two nucleotide analog drugs. The study also demonstrates that the possible biochemical mechanism of cellular toxicity and drug synergism is attributed to induction of apoptosis following drug treatment and the onset of the apoptotic cascade is primarily regulated by p21/WAF-I, which is transcriptionally activated by p53 following DNA damage. The anti-apoptotic protein, bcl-2, seemed to have no effect in inhibiting apoptosis following treatment with the two or three drug regimens in this in vitro leukemia model. The three-drug combination induced greater cellular apoptosis than the two-drug combination or Taxotere monotherapy. We conclude that the greater drug synergism observed in human leukemic cells, sensitive or resistant to ara-C, by Fludarabine + ara-C + Taxotere can be explained by the greater oligonucleosomal DNA fragmentation indicative of increased cellular apoptosis. The mechanism of this increased cytotoxic action is due to the upregulation of p53 and p21/WAF-1 with a down regulation of bcl-2. These studies are encouraging, and testing this three drug regimen in a clinical setting may result in improved antileukemic therapies.

Calculation of van't Hoff enthalpy associated with aspirin-induced change in liposomal membrane anisotropy.

The lipid disordering effect of aspirin on the liposomal membrane of dipalmitoyl phosphatidyl choline has recently been studied using the fluorescence polarization method. From the anisotropy-temperature curve, we have calculated here the associated change in van't Hoff enthalpy. Since the fluorescence technique requires a very small amount of sample (10(-4) M), this method of enthalpy calculation compares well and is advantageous over the standard calorimetric methods.

Photoinduced proton transport mechanism in merocyanine-dye-probed planar lipid membranes.

Planar lipid membranes were used to study photovoltage generation after the incorporation of various merocyanine dyes. These dyes undergo photochemical isomerization on illumination and can act as a photon-driven facilitated proton transport system under suitable conditions. This system has the advantage of preventing back recombination of the photodissociated charges, thus improving its storage capacity. A sufficiently high photovoltage, with a long storage time and good reproducibility, was obtained with these dyes. The spectral studies indicate the formation of a 1:1 complex between dye and lipid molecules. Our results show that the strength and stability of complex formation increase with the hydrophobicity of the dye which, in turn, increase the magnitude and storage of the photovoltage generated in the system.

Pharmacodynamic studies (PD) of didanosine (ddI) alone and in combination with azidothymidine (AZT) in human T-cells; a stochastic biochemical approach to antiretroviral nucleoside drug combination in inhibiting HIV-reverse transcriptase (RT).

Didanosine (ddI) is used in the treatment of HIV-1 infection alone and in combination with azidothymidine (AZT). When combined with AZT, patients exhibit improved patterns of surrogate markers after sequential combination regimens of ddI and AZT compared to either drug monotherapy. We have investigated the biochemical mechanism(s) of this synergistic drug combination in human PBMC cells and in human T-cell lines sensitive and resistant to AZT due to lack of thymidine kinase (TK). DdI is preferentially activated to its triphosphate anabolite, ddATP, at 3:1 ratio in human T-lymphocytes compared to monocytes from the same individual. There are no apparent differences in the intracellular concentrations of ddATP in Jurkat/0 and Jurkat/AZT-10, an AZT resistant human T-cell line, when ddI is administered alone or in combination with AZT, hence there appears to be a case of collateral sensitivity. Intracellular increases of AZTTP concentrations in patient's PBMC cells have been determined clinically after AZT alone and in a combination regimen with ddI. A stochastic biochemical model has been developed that estimates the velocity of HIV-RT under uninhibited and inhibited conditions by the active anabolites, AZTTP and ddATP. This model provides a rational explanation for the greater inhibition of HIV-RT in the presence of both inhibitors, AZTTP and ddATP, as compared to the presence of either anabolite triphosphate alone. Expanding this model to describe the inhibition of HIV-RT in the presence of three competitive inhibitors, AZTTP, ddATP and 3TCTP demonstrated that the presence of these HIV-RT inhibitors resulted in an even greater inhibition of this viral enzyme necessary for HIV integration and replication. Hence, a more effective inhibition of HIV-RT enzyme is achieved by the combination of the three drugs, AZT, ddl and 3TC. In an effort to verify this model with experimental data the kinetics of HIV-RT were studied in the absence and after inhibition by AZTTP or ddATP alone, both AZTTP + ddATP or AZTTP + ddATP + 3TCTP. Treatment of HIV-RT with high concentrations of these triphosphate inhibitors, as high as 3Kis, inhibited this enzyme to greater than 90% of untreated control. However, a small percentage of residual HIV-RT, 6%, was uninhibited even after exposure to 3Ki concentrations of each inhibitor. These studies strongly suggested that: 1) AZT plus ddI or AZT plus ddI plus 3TC are synergistic at the active anabolite level against HIV-RT; 2) the combination of the three nucleoside analog drugs (AZT, ddI 3TC) is needed for more effective inhibition of HIV-RT; 3) that the combination of the triphosphates at concentrations much greater than those pharnacologically achieved in T-Cells or PBMC under treatment conditions did not inhibit completely HIV-RT. Hence, the three nucleoside HIV-RT inhibitors must be combined with other classes of antiviral drugs or T-cell specific inhibitor drugs.

Body iodine status in school children and availability of iodised salt in Calcutta.

Success of Universal Salt Iodization (USI) programme depends on availability of iodised salt to consumers, which should be reflected in their body iodine status. From a monitoring study in Calcutta, it was found that all packed salts were iodised and most of them (98.1% at household level and 93.6% at retailers' outlets) had iodine at a level of > or = 15 ppm. Of the loose salts, 34.6% at household level and 19.9% at retailers' outlet had iodine level < 15 ppm. A few number (0.5% at household level and 1.0% at retailers' outlets) of salts had no iodine. To ascertain the impact of consumption of iodised salt iodine excreted in urine (UIE) was measured in school children of age between 8-12 years of south, east, west, north and central parts of Calcutta. 22.95% of male children and 31.81% of female children had urinary iodine level less than 50 micrograms/l, which is cut off figure of public health concern. Children from poor slum areas were found to be at greater risk.

PIP: This paper presents a monitoring study on the availability of iodized salt at retailers' outlets and at the household level in Calcutta, as well as the impact of its consumption among school children aged 8-12 years. The children were physically examined for 3 grades of goiter. Urine samples were collected to estimate iodine excretion. Various types of salts were gathered from retailers' outlets located within a 0.5 km radius of the school that the children attended. Spot test kit and iodimetric titration methods were used in monitoring the availability of iodized salt. Results showed that all packed salts were iodized and that a majority of them (98.1% at the household level and 93.6% at the retailers' outlet level) had iodine levels of 15 ppm or higher. Only a small percentage of salts (0.5% at the household level and 1.0% at the retailers' outlet level) had no iodine content. As to the urinary iodine content among school children, 22.95% of males and 31.81% of females had urinary iodine level less than 50 mcg/l. 77% of male children and 69% of female children had satisfactory urinary iodine levels (50 mcg/l). The results confirmed the success of the Universal Salt Iodization (USI) program with regard to the availability of iodized salt.

Potency dependent activity of homeopathic nanomedicine- classical and quantum electrodynamical approach

The effect of homeopathic medicine on biological and physical system is directly related to its potency [1]. However, from physico-chemical point of view it is difficult to explain this effect at such high dilution, as then the existence of even trace amount of particle is questionable. It has been reported that during the process of potentization, a large amount of mechanical energy gets transferred to the medium due to succussion [2]. This energy in all probability reduces the size of the drug aggregates. The drug then penetrates easily through the membrane barrier, and thereby gives rise to enhanced activity of the medicine. It has been experimentally proved by us and supported by others that indeed a reduction of size of the aggregates takes place with increase in potency [3]. Using five different homeopathic medicines, their sizes at three different potencies have been estimated and a general mathematical expression relating the size of the particle (Y) and the corresponding potency (X) has been derived as follows Y = a X -n. (AU)

Effect of nicotinic acid on microviscosity in mixed liposomal system of lecithin and sphingomyelin.

In rat liver plasma membrane, the molar ratio of sphingomyelin and phospholipid is approximately 1:4, whereas, the molar ratio of phospholipid and cholesterol is 3:1. Considering this ratio to be typical for a real biological membrane, we have studied the effect of anticholesterol and the vasodialatory drug nicotinic acid (NA) on the fluidity profile of a liposomal system of lipids mixed in this ratio using the fluorescence polarization probe 1,6-diphenyl-1-1,3,5-hexatriene. The study reveals that when NA is added to the aqueous dispersion of the mixed lipid system (molar ratio of lipid:NA, 1:1) it creates a more fluid environment for the probe molecule and modifies the fluidity profile of the cholesterol-incorporated liposomal system by eliminating the effect of cholesterol to some extent. The drug also affects the activation energy of diffusion of this system. These results on fluidity have been compared with those in cases of liposomes of individual lipids. The effect of NA on fluidity may be attributed to a mechanical interaction of the drug molecules with the lipid molecules.