A circular plate kept zero initial temperature is heated for a certain interval of time over a concentric circular region of the upper face. Deflection is obtained by using Laplace transform ...technique. Taking the plate material to be aluminium, central deflection is obtained for several values of time and the results shown graphically.
This is a basic text of Management Accountacy that approaches the subject from the vantage point of various disciplines - management, financial and cost accountancy, and mathematics, among others. ...Each topic is presented in detail with the help of illustrations and sample problems and solutions.
Non-steroidal anti-inflammatory drugs (NSAIDs) of oxicam group are not only effective as anti-inflammatory agents but also show diverse functions. Their principal targets are cyclooxygenases, which ...are membrane-associated enzymes. To bind with the targets these drugs have to pass through the membrane and hence their interactions with biomembranes should play a major role in guiding their interactions with cyclooxygenases. Here we have studied the interactions of three NSAIDs of oxicam group viz. piroxicam, meloxicam and tenoxicam with micelles having different headgroup charges, as simple membrane mimetic systems. Spectroscopic methods have been used to understand the interaction of these drugs with Cetyl
N,
N,
N-trimethyl ammonium bromide (cationic), Sodium dodecyl sulphonate (anionic) and Triton X-100 (neutral) micelles. Our results demonstrate that the environment of the drugs i.e. the nature of the micelles plays a decisive role in choosing a specific prototropic form of the drugs for incorporation. Additionally it induces a switch over or change between different prototropic forms of piroxicam, which is correlated with the change in their reactivities in presence of different surface charges, given by the change in p
K
a values. These results together, indicate that in vivo, the diverse nature of biomembranes might play a significant role in choosing the particular form of oxicam NSAIDs that would be presented to their targets.
Small unilamellar vesicles (SUVs) formed by the dimyristoylphosphatidylcholine (DMPC), a phospholipid; serve as a membrane mimetic system that can be used to study the effect of absence of net ...surface charges on drug–membrane interaction. The targets of non-steroidal anti-inflammatory drugs (NSAIDs) are cyclooxygenases, which are membrane active enzymes. Hence, to approach their targets NSAIDs have to pass different bio-membranes. Different membrane parameters are expected to guide the first level of interaction of these drugs before they are presented to their targets. Our earlier studies have demonstrated the crucial role of surface charges of membrane mimetic systems like micelles and mixed micelles on the interaction of oxicam NSAIDs. In order to see whether net surface charges of membranes are essential for the interaction of oxicam NSAIDs, we have studied the incorporation of two oxicam NSAIDs, viz., piroxicam and meloxicam in DMPC vesicles using the intrinsic fluorescence properties of the drugs. To see whether different prototropic forms of the drugs can interact with DMPC vesicles, studies were carried out under different pH conditions. Transmission electron microscopy (TEM) was used to characterize the SUVs those were formed at different pH values. Steady state fluorescence anisotropy measurements show that both forms of the two drugs, viz., global neutral and anion can be incorporated into the DMPC vesicles. Partition coefficient (
K
P) between DMPC and the aqueous buffer used has been calculated in all cases from fluorescent intensity measurements. The
K
P values for the neutral and anionic forms of piroxicam are 219.0 and 25.8, respectively, and that for meloxicam are 896.7 and 110.2, respectively. From the
K
P values it is evident that irrespective of the nature of the prototropic forms, meloxicam has a higher
K
P value than piroxicam. This correlates with the previously calculated log
K
P values between
n-octanol and aqueous phase, which demonstrates that in absence of net surface charges of DMPC vesicles the hydrophobic interaction is the principal driving force for incorporation. Our results imply that for bio-membranes having no net surface charges hydrophobic effect plays a principal role to guide these NSAIDs to their targets.
Transmission of HIV-1 is predominantly by heterosexual contact in sub-Saharan Africa, where sexually transmitted diseases (STDs) are also common. Epidemiological studies suggest that STDs facilitate ...transmission of HIV-1, but the biological mechanism remains unclear. We investigated the hypothesis that STDs increase the likelihood of transmission of HIV-1 through increased concentration of the virus in semen.
HIV-1 RNA concentrations were measured in seminal and blood plasma from 135 HIV-1-seropositive men in Malawi; 86 had urethritis and 49 controls did not have urethritis. Men with urethritis received antibiotic treatment according to the guidelines of the Malawian STD Advisory Committee. Samples were analysed at baseline and at week 1 and week 2 after antibiotic therapy in urethritis patients, and at baseline and week 2 in the control group.
HIV-1-seropositive men with urethritis had HIV-1 RNA concentrations in seminal plasma eight times higher than those in seropositive men without urethritis (12·4
vs 1·51×10
4 copies/mL, p=0·035), despite similar CD4 counts and concentrations of blood plasma viral RNA. Gonorrhoea was associated with the greatest concentration of HIV-1 in semen (15·8×10
4 copies/mL). After the urethritis patients received antimicrobial therapy directed against STDs, the concentration of HIV-1 RNA in semen decreased significantly (from 12·4×10
4 copies/mL to 8·91×10
4 copies/mL at 1 week p=0·03 and 4·12×10
4 copies/mL at 2 weeks p=0·0001). Blood plasma viral RNA concentrations did not change. There was no significant change in seminal plasma HIV-1 RNA concentrations during the 2-week period in the control group (p=0·421).
These results suggest that urethritis increases the infectiousness of men with HIV-1 infection. HIV-1-control programmes, which include detection and treatment of STDs in patients already infected with HIV-1, may help to curb the epidemic. Targeting of gonococcal urethritis may be a particularly effective strategy.
We report on the risk of miscarriage with high- and low-dosage periconceptional folic acid (FA) supplementation from a double-blind randomized clinical trial for prevention of orofacial cleft ...recurrence in Brazil.
Women at risk of recurrence of orofacial clefts in their offspring were randomized into high (4 mg/day) and low (0.4 mg/day) doses of FA supplementation. The women received the study pills before pregnancy, and supplementation continued throughout the first trimester. Miscarriage rates were compared between the two FA groups and with the population rate.
A total of 268 pregnancies completed the study protocol, with 141 in the 4.0-mg group and 127 in the 0.4-mg group. The miscarriage rate was 14.2% in the low-dose FA group (0.4 mg/day) and 11.3% for the high-dose group (4 mg/day) (P=0.4877). These miscarriage rates are not significantly different from the miscarriage rate in the Brazilian population, estimated to be around 14% (P=0.311).
These results indicate that high-dose FA does not increase miscarriage risk in this population and add further information to the literature on the safety of high FA supplementation for prevention of birth defect recurrence.
Oxicam group of non steroidal anti-inflammatory drugs has been chosen as a prototype molecular group that shows diverse biological functions and dynamic structural features. Photophysical studies of ...three drugs from this group viz., piroxicam, meloxicam and tenoxicam have been carried out in different solvents with varying polarity, H-bond character and viscosity. The spectral responses of different prototropic forms of these drugs towards varying solvent parameters have been studied, with the aim to characterize their interaction in biomimetic environment non-invasively. The nature of the lowest transition has been identified. The extinction coefficient, quantum yield and viscosity dependence on the nature of the solvents, all indicate the extreme sensitivity of these drugs to their microenvironment.
Cervical cancer, a rare outcome of high-risk human papillomavirus (HPV) infection, disproportionately affects African American women, who are about twice more likely than European American women to ...die of the disease. Most cervical HPV infections clear in about one year. However, in some women HPV persists, posing a greater risk for cervical dysplasia and cancer. The Carolina Women's Care Study (CWCS) was conducted to explore the biological, genetic, and lifestyle determinants of persistent HPV infection in college-aged European American and African American women. This paper presents the initial results of the CWCS, based upon data obtained at enrollment.
Freshman female students attending the University of South Carolina were enrolled in the CWCS and followed until graduation with biannual visits, including two Papanicolaou tests, cervical mucus collection, and a questionnaire assessing lifestyle factors. We recruited 467 women, 293 of whom completed four or more visits for a total of 2274 visits.
CWCS participants were 70% European American, 24% African American, 3% Latina/Hispanic, and 3% Asian. At enrollment, 32% tested positive for any HPV. HPV16 infection was the most common (18% of infections). Together, HPV16, 66, 51, 52, and 18 accounted for 58% of all HPV infections. Sixty-four percent of all HPV-positive samples contained more than one HPV type, with an average of 2.2 HPV types per HPV-positive participant. We found differences between African American and European American women in the prevalence of HPV infection (38.1% African American, 30.7% European American) and abnormal Papanicolaou test results (9.8% African-American, 5.8% European American). While these differences did not reach statistical significance at enrollment, as the longitudinal data of this cohort are analyzed, the sample size will allow us to confirm these results and compare the natural history of HPV infection in college-aged African American and European American women.
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