In vitro and in silico approaches to evaluate the pharmacokinetics and pharmacodynamics of combination antibiotic therapy against drug-resistant bacteria

This thesis focuses on combating antibacterial resistance by developing novel in vitro and in silico techniques. In vitro techniques such as in vitro pharmacodynamic (IVPD) modeling are powerful tools for investigating pharmacokinetic and pharmacodynamic response of antibiotics against bacteria. The standard IVPD model in the literature works for simulating monotherapy and combination therapy of drugs having similar half live. But it does not work for combination therapy of drugs having different half live. The method present in the literature for combination therapy of drugs with different half live was described by Blaser. By utilizing Blaser’s method, it was observed that the concentration of drug having a longer half-life could not be achieved as expected in vivo. Therefore, it was essential to develop a novel in vitro pharmacodynamic model to address this limitation. The novel IVPD model in this thesis has overcome this issue by varying the infusion rate at which the drug with longer half-life was being supplemented to the central vessel. The change in infusion rate was calculated to mimic the in vivo plasma concentration of the longer half-life drug. The novel IVPD model was verified by running a 48 hour experiment where the concentration of drug with longer half-life (ceftriaxone) was monitored. Another aspect of this research was dedicated to developing a physiologically based pharmacokinetic and pharmacodynamic (PBPK-PD) model for combination therapy of amicrobial medications acting synergistically (ampicillin and ceftriaxone). PBPK modeling is a dynamic method that predicts in vivo systemic drug exposure in humans based on the compound’s physicochemical properties and absorption, distribution, metabolism and excretion (ADME) characteristics. Interlinking it with the pharmacodynamic model would help to understand the change in pharmacodynamic response caused due to alterations in the pharmacokinetics of drug that impact systemic exposure. An advantage of developing PBPK-PD model for combination therapy is it can act as a predictive tool to optimize dosing regimen and understand the pharmacodynamic response in special populations (renal impaired patients, pediatrics, pregnant women, etc.). To develop the PBPK-PD model, substrate profiles for ampicillin and ceftriaxone were first created and verified in healthy volunteers against published literature. Verification was performed by visual predictive check and by calculating the fold error for maximum concentration (Cmax) and area under the curve (AUC). A custom PD model was developed using lua script code which can simulate a pharmacodynamic response for drugs acting synergistically. The PBPK model was interlinked with the PD model. The PBPK-PD model was verified against in vitro results published in the literature. The PD end point was the observed decrease in bacterial count over a period of 72 hours. A dosing regimen of ampicillin 2g q 4 hours and ceftriaxone 2g q 12 hours was simulated using the PBPK-PD model. It was observed that the PBPK-PD model developed in this research could capture the in vitro pharmacodynamic experiment data. Once verified, the PBPK-PD model was extended to a population of severe renal impaired patients. PBPK-PD model was used to justify the change in dose frequency of ampicillin when given in combination with ceftriaxone in severe renal impaired patients’ population. Two dosing regimens were simulated in severe renal impaired patients: 1) ampicillin 2g q 8 hours and ceftriaxone 2g q 12 hours, and 2) ampicillin 2g q 6 hours and ceftriaxone 2g q 12 hours. In a patient population with renal impairment a regimen comprised of ampicillin IV 2000 mg every q-6 hours and ceftriaxone IV 2000 mg q-12 hours achieved complete eradication of bacteria. The novel PBPK-PD model created in this dissertation research is of clinical significance as an in silico approach can be used to optimizing dosing regimens in special patient populations being treated with a combination of antimicrobial drugs acting synergistically

The Submerged Scope of the Spanish Flu: Negotiating Representational Challenges in Willa Cathers One of Ours

The pandemic of 1918 or more famously the Spanish flu remains a dark and disruptive phenomenon a scourge in the face of time and history But what makes it most intriguing is its own oxymoronic entity-its own absent-presence an experience that was simultaneously ubiquitous and hidden Such exclusion when understood as deliberate remains at the heart of discourses of power and domination Human civilization is rife with many such practices be it indiscriminate exploitation of the environment or the discrimination on grounds of race caste colour gender sexuality et al- all based on a systemic delegitimization of discarded negatives Butler Representation when empowered with a disruptive force that can push through state sanctioned borders and mainstream interpretive constructs can emerge as alternative frames that can see through the suppressed Lifting the veil of the archival dust ambient upon long forgotten stories will enable us to excavate narrative possibilities from all that has been silenced granting them a voice that is long due This article will be structured into two cluster of materials the first part will briefly document the extent and spread of the contagion tracing its evolution from a miasmic atmospheric entity shifting in waves towards becoming a horrifying visible realit

Model dependence of the multi-transonic behavior, stability properties and corresponding acoustic geometry for accretion onto a spinning black hole

Multi-transonic accretion for a spinning black hole has been compared among different disc geometries within post Newtonian pseudo potential framework. The variation of stationary shock characteristics with black hole spin has been studied in details for all the disc models and compared for adiabatic as well as for isothermal scenario. The variations of surface gravity with spin for all these cases have also been investigated.Comment: 18 pages. 19 figure

Hybrid solar cell with TiO2 film: BBOT polymer and copper phthalocyanine as sensitizer

An organic-inorganic hybrid solar cell was fabricated using Titanium dioxide (TiO2): 2,5-bis(5-tert-butyl-2-benzoxazolyl) thiophene (BBOT) film and Copper Phthalocyanine (CuPc) as a sensitizer. BBOT was used in photodetector in other reported research works, but as per best of our knowledge, it was not implemented in solar cells till date. The blend of TiO2: BBOT blend was used to fabricate the film on ITO-coated glass and further a thin layer of CuPc was coated on the film. This was acted as photoanode and another ITO coated glass with a platinum coating was used as a counter electrode (cathode). An optimal blend of acetonitrile (solvent) (50-100%), 1,3-dimethylimidazolium iodide (10-25%), iodine (2.5-10%) and lithium iodide, pyridine derivative and thiocyanate was used as electrolytes in the hybrid solar cell. The different structural, optical and electrical characteristics were measured. The Hybrid solar cell showed a maximum conversion efficiency of 6.51%

Comparative evaluation of anti-diabetic activity of fresh juice and ethanolic extract of Sunderban mangrove Rhizophora mucronata Lam. leaves in animal model

Background: Mangrove flora possess compounds with potential medicinal values with unique bioactive components. Traditionally Rhizophora mucronata, a mangrove has been used extensively for the treatment of diabetes. Studies revealed that, the leaves of Rhizophora (Bhora) had promising anti-diabetic action in rat model.Methods: A comparative analysis of the anti-diabetic action of fresh juice and ethanolic extract of Rhizophora mucronata leaves was carried out in Streptozotocin induced diabetic model and the different biochemical parameters were evaluated.Results: Present research explored a comparative analysis of the anti-diabetic action of fresh juice and ethanolic extract of leaves of Rhizophora mucronata Lam. in Streptozotocin induced diabetic model. The ethanolic extract showed more potent effect in lowering the elevated blood sugar in the diabetic rats, 200mg/kg was the most effective dose for both the extracts. The ethanol extract was more beneficial having potent lipid lowering action along with anti-hyperglycemic property.Conclusions: This supports the scientific validation for using Rhizophora mucronata leaves in the treatment of diabetes as traditional folk medicine. Identification of the bioactive molecule is under process

Role of inflammation as reflected by serum hsCRP and ferritin level in major depressive disorder

Background: The relationship between depression and inflammation has been strengthened by different studies for which Immune Cytokine Mechanism has been proposed to explain pathogenesis of depression.Methods: The role of inflammation in major depressive disorder (MDD) has been evaluated in this study among 101 patients suffering from MDD along with 106 age and sex matched control subjects. Two well known acute phase reactant proteins namely hsCRP and Ferritin were assayed in all study subjects by Enzyme Immuno Assay method.Results: Concentration of hsCRP in serum was found to be significantly increased in all patients suffering from MDD whereas Ferritin level was found to be significantly decreased in male MDD subjects only (male: 70.6 ng/ml±53.54 ng/ml in MDD vs 100.16 ng/ml±39.93 in controls; female: 38.43 ng/ml±11.2 in MDD vs 39.93 ng/ml±15.0 in controls). There was no significant alteration of the parameters among different grades of MDD. The possibility of these two parameters to be used as biomarkers has also been evaluated by ROC curve.Conclusions: The significant change in hsCRP & Ferritin which is not associated with grade wise alteration suggests that probably inflammation is the early event which causes depression. Therefore no gradual change is observed with increase in severity of the disease. hsCRP can be used as a biomarker of Inflammation in MDD cases

Supplements to article: A novel transcription complex that selectively modulates apoptosis of breast cancer cells through regulation of FASTKD2

The materials provided here are supplemental tables and figures to an article to be published in 'Molecular and Cellular Biology.'(This refers to the article.) We previously reported that expression of NRIF3 (Nuclear Receptor Interacting Factor-3) rapidly and selectively leads to apoptosis of breast cancer cells. DIF-1 (a.k.a IRF-2BP2), the cellular target of NRIF3, was identified as a transcriptional repressor and DIF-1 knockdown leads to apoptosis of breast cancer cells but not other cell types. Here, we identify IRF2BP1 (Interferon Regulatory Factor-2 Binding Protein 1) and EAP1 (Enhanced At Puberty 1) as important components of the DIF-1 complex mediating both complex stability and transcriptional repression. This interaction of DIF-1, IRF2BP1, and EAP1 occurs through the conserved C4 zinc-fingers of these proteins. Microarray studies were carried out in breast cancer cell lines engineered to conditionally and rapidly increase the levels of the Death Domain region of NRIF3 (DD1). The DIF-1 complex was found to repress FASTKD2, a putative pro-apoptotic gene, in breast cancer cells and to bind to the FASTKD2 gene by chromatin immunoprecipitation. FASTKD2 knockdown prevents apoptosis of breast cancer cells from NRIF3 expression or DIF-1 knockdown while expression of FASTKD2 leads to apoptosis of both breast and non-breast cancer cells. Thus, regulation of FASTKD2 by NRIF3 and the DIF-1 complex acts as a novel death switch that selectively modulates apoptosis in breast cancer

Deuterium oxide stabilizes conformation of tubulin: a biophysical and biochemical study

The present study was aimed to elucidate the mechanism of stabilization of tubulin by deuterium oxide $(D_2O)$. Rate of decrease of tryptophan fluorescence during aging of tubulin at $4^oC$ and $37^oC$ was significantly lower in $D_2O$ than in $H_2O$. Circular dichroism spectra of tubulin after incubation at $4^oC$, suggested that complete stabilization of the secondary structure in $D_2O$ during the first 24 hours of incubation. The number of available cysteine measured by DTNB reaction was decreased to a lesser extent in $D_2O$ than in $H_2O$. During the increase in temperature of tubulin, the rate of decrease of fluorescence at 335 nm and change of CD value at 222 nm was lesser in $D_2O$. Differential Scanning calorimetric experiments showed that the $T_m$ values for tubulin unfolding in $D_2O$ were $58.6^oC$ and $62.17^oC$, and in $H_2O$ those values were $55.4^oC$ and $59.35^oC$

"The fruits of independence": Satyajit Ray, Indian nationhood and the spectre of empire

Challenging the longstanding consensus that Satyajit Ray's work is largely free of ideological concerns and notable only for its humanistic richness, this article shows with reference to representations of British colonialism and Indian nationhood that Ray's films and stories are marked deeply and consistently by a distinctively Bengali variety of liberalism. Drawn from an ongoing biographical project, it commences with an overview of the nationalist milieu in which Ray grew up and emphasizes the preoccupation with colonialism and nationalism that marked his earliest unfilmed scripts. It then shows with case studies of Kanchanjangha (1962), Charulata (1964), First Class Kamra (First-Class Compartment, 1981), Pratidwandi (The Adversary, 1970), Shatranj ke Khilari (The Chess Players, 1977), Agantuk (The Stranger, 1991) and Robertsoner Ruby (Robertson's Ruby, 1992) how Ray's mature work continued to combine a strongly anti-colonial viewpoint with a shifting perspective on Indian nationhood and an unequivocal commitment to cultural cosmopolitanism. Analysing how Ray articulated his ideological positions through the quintessentially liberal device of complexly staged debates that were apparently free, but in fact closed by the scenarist/director on ideologically specific notes, this article concludes that Ray's reputation as an all-forgiving, ‘everybody-has-his-reasons’ humanist is based on simplistic or even tendentious readings of his work