Urinary Tract Infection in Renal Allograft Recipents

Renal replacement therapy in the form of renal transplantation (RT) is the treatment of choice in these patients. Various factors influence the graft survival, infections being most common. Infections account for 16% of patient deaths and 7.7% of death censored graft failure in renal transplant patients. Urinary tract infection (UTI) is the most common infectious complication accounting for 45–72% of all infections. According to few studies UTI may have a negative impact over the long term survival of renal allograft. There are multiple factors that predispose these patients to UTI. Elderly age group, female gender, increased duration of catheterization and anatomical abnormalities of the urinary tract are most common predisposing factors. E. coli is the most frequently isolated organisms from the urine of these patients. We would proceed further with two cases which presented as UTI in post-transplant period. The first patient transplanted (living donor related) for diabetes induced end stage renal disease had developed UTI 4 years post-transplant. The other patient underwent deceased donor renal transplant for adult polycystic disease related chronic kidney disease, presented 2 years post-transplant with UTI

Pathology Associated with Hormones of Adrenal Cortex

Adrenal gland is an endocrine organ comprising of an outer cortex and inner medulla. These secrete various hormones that have a vital role in maintaining the normal homeostasis of the body. Lesions of adrenal cortex are quite common to encounter and most of these are related to the hormones secreted by three layers of adrenal cortex: the zona glomerulosa, the zona fasciculata, and the zona reticularis. Also it is very infrequent to encounter metastatic lesions in the adrenal glands too. So it is very important as a part of a clinician as well as a pathologist to know the pattern in which these hormones are secreted along with their physiological roles. Thus this chapter includes the disease that are related to excess as well as deficiencies of the hormones secreted by adrenal cortex. The chapter also includes various genetic syndromes that are associated with the disorders associated with hormones of adrenal cortex. The last part of the chapter includes a brief description of various benign as well as malignant lesions, the pathological as well as the etiological aspects and the hormonal abnormalities associated. This chapter thus mainly focuses on the pathology associated with the adrenal cortex and hormones secreted by the various layers of adrenal cortex

Revival of Superconductivity by Y3+/Ca2+ substitution in YBa2Cu2.7Co0.3O7 without reported phase transformation

Results of phase formation, resistivity (r), and thermo-electric power (S), are reported on Y1-xCaxBa2Cu2.7Co0.3O7 compounds with x = 0.1 and 0.2. Pristine compound i.e. without Co or Ca substitution crystallizes in orthorhombic structure with space group P/mmm. Cu-site Co substituted compound i.e. YBa2Cu2.7Co0.3O7 is tetragonal. With simultaneous doping of Ca at Y site in Co substituted compound i.e. Y1-xCaxBa2Cu2.7Co0.3O7 the tetragonal nature still remains. r(T) measurements showed superconducting transition temperature (Tc) to decrease from 90K (YBa2Cu3O7) to 33 K for YBa2Cu2.7Co0.3O7 which with further Ca substitution increases from 33K to 53K (Y0.9 Ca0.1Ba2Cu2.7Co0.3O7) and 67 K for Y0.8 Ca0.2Ba2Cu2.7Co0.3O7. Tc decreases first with Cu-site Co substitution by hole-filling and later recovers by simultaneous hole creation by Y site Ca substitution. Room temperature thermoelectric power S(300 K), which is an indirect measure of mobile carriers shows the decrease of carriers with Co doping and creation by Ca substitution. Our results demonstrate the hole filling by Co substitution is compensated by simultaneous Ca substitution.Comment: 10 pages of TEXT and Fig

Revival of superconductivity by Y3+/Ca2+ substitution in YBa2Cu2.7Co0.3O7 without reported phase transformation

Results of phase formation, resistivity (r), and thermo-electric power (S), are reported on Y1-xCaxBa2Cu2.7Co0.3O7 compounds with x = 0.1 and 0.2. Pristine compound i.e. without Co or Ca substitution crystallizes in orthorhombic structure with space group P/mmm. Cu-site Co substituted compound i.e. YBa2Cu2.7Co0.3O7 is tetragonal. With simultaneous doping of Ca at Y site in Co substituted compound i.e. Y1-xCaxBa2Cu2.7Co0.3O7 the tetragonal nature still remains. r(T) measurements showed superconducting transition temperature (Tc) to decrease from 90K (YBa2Cu3O7) to 33 K for YBa2Cu2.7Co0.3O7 which with further Ca substitution increases from 33K to 53K (Y0.9 Ca0.1Ba2Cu2.7Co0.3O7) and 67 K for Y0.8 Ca0.2Ba2Cu2.7Co0.3O7. Tc decreases first with Cu-site Co substitution by hole-filling and later recovers by simultaneous hole creation by Y site Ca substitution. Room temperature thermoelectric power S(300 K), which is an indirect measure of mobile carriers shows the decrease of carriers with Co doping and creation by Ca substitution. Our results demonstrate the hole filling by Co substitution is compensated by simultaneous Ca substitution

Mitochondrial Cytopathies of the Renal System

Mitochondria are major intracellular organelles with a variety of critical roles like adenosine triphosphate production, metabolic modulation, generation of reactive oxygen species, maintenance of intracellular calcium homeostasis, and the regulation of apoptosis. Mitochondria often undergo transformation in both physiological and pathological conditions. New concepts point that mitochondrial shape and structure are intimately linked with their function in the kidneys and diseases related to mitochondrial dysfunction have been identified. Diseases associated with mitochondrial dysfunction are termed as “mitochondrial cytopathies”. Evidence support that there is a role of mitochondrial dysfunction in the pathogenesis of two common pathways of end-stage kidney disease, namely, chronic kidney disease (CKD) and acute kidney injury (AKI). Mitochondrial cytopathies in kidneys mainly manifest as focal segmental glomerular sclerosis, tubular defects, and as cystic kidney diseases. The defects implicated are mutations in mtDNA and nDNA. The proximal tubular cells are relatively vulnerable to oxidative stress and are therefore apt to suffer from respiratory chain defects and manifest as either loss of electrolyte or low-molecular-weight proteins. Patients with mitochondrial tubulopathy are usually accompanied by myoclonic epilepsy and ragged red muscle fibers (MERRF), and Pearson’s, Kearns-Sayre, and Leigh syndromes. The majority of genetic mutations detected in these diseases are fragment deletions of mtDNA. Studies have shown significantly increased ROS production, upregulation of COX I and IV expressions, and inactivation of complex IV in peripheral blood mononuclear cells of patients with stage IV–V CKD, thereby demonstrating the close association between mitochondrial dysfunction and progression to CKD. Furthermore, the mechanisms that translate cellular cues and demands into mitochondrial remodeling and cellular damage, including the role of microRNAs and lncRNAs, are examined with the final goal of identifying mitochondrial targets to improve treatment of patients with chronic kidney diseases

Impact of Zn substitution on phase formation and superconductivity of Bi1.6Pb0.4 Sr2Ca2Cu3-xZnxO10 with x = 0.0, 0.015, 0.03, 0.06, 0.09 and 0.12

Samples of series Bi1.6Pb0.4Sr2Ca2Cu3-xZnxO10 with x = 0.0, 0.015, 0.03, 0.06, 0.09 and 0.12 are synthesized by solid-state reaction route. All the samples crystallize in tetragonal structure with majority (> 90%) of Bi-2223 (Bi2Sr2Ca2Cu3O10) phase (c-lattice parameter ~ 36 A0). The proportion of Bi-2223 phase decreases slightly with an increase in x. The lattice parameters a and c of main phase (Bi-2223) do not change significantly with increasing x. Superconducting critical transition temperature (Tc) decreases with x as evidenced by both resistivity [(T)] and AC magnetic susceptibility [(T)] measurements. Interestingly the decrement of Tc is not monotonic and the same saturates at around 96 K for x > 0.06. In fact Tc decreases fast (~10K/at%) for x = 0.015 and 0.03 samples and later nearly saturates for higher x values. Present results of Zn doping in Bi-2223 system are compared with Zn doped other HTSC (High temperature superconducting) systems, namely the RE-123 (REBa2Cu3O7) and La-214 ((La,Sr)2CuO4).Comment: 12, pages of text and Figs. TO APPEAR IN Mod. Phys. Lett. B (2005)

Modification of Rifamycin Polyketide Backbone Leads to Improved Drug Activity Against Rifampicin-Resistant Mycobacterium tuberculosis

Rifamycin B, a product of Amycolatopsis mediterranei S699, is the precursor of clinically used antibiotics that are effective against tuberculosis, leprosy and AIDS related mycobacterial infections. However, prolonged usage of these antibiotics has resulted in the emergence of rifamycin resistant strains of Mycobacterium tuberculosis. As part of our effort to generate better analogs of rifamycin, we substituted the acyltransferase (AT) domain of module 6 of rifamycin polyketide synthase (rifPKS) with that of module 2 of rapamycin PKS. The resulting mutants (rifAT6::rapAT2) of A. mediterranei S699 produced new rifamycin analogs, 24-desmethylrifamycin B and 24-desmethylrifamycin SV, which contained modification in the polyketide backbone. 24-desmethylrifamycin B was then converted to 24-desmethylrifamycin S, whose structure was confirmed by MS, NMR, and X-ray crystallography. Subsequently, 24-desmethylrifamycin S was converted to 24-desmethylrifampicin, which showed excellent antibacterial activity against several rifampicin-resistant M. tuberculosis strains.This research was originally published in the Journal of Biological Chemistry. Nigam, A., Almabruk, K. H., Saxena, A., Yang, J., Mukherjee, U., Kaur, H., ... & Lal, R. Modification of Rifamycin Polyketide Backbone Leads to Improved Drug Activity against Rifampicin-resistant Mycobacterium tuberculosis. Journal of Biological Chemistry. 2014. 289:21142-21152. © the American Society for Biochemistry and Molecular Biology. This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by The American Society for Biochemistry and Molecular Biology, Inc., and can be found at: http://www.jbc.org/Keywords: Domain Swapping, Polyketide Synthase, Rifamycin analogs, Multiple Drug Resistant, 24-desmethylrifamyci

Study of magnetic behaviour in Ru-based superconducting ferromagnets

Phenomena arising due to interaction between magnetic phases and superconductivity are one of the most intensively studied and intriguing fields of research due to its relevancy to superconducting and spin electronics, colossal magneto-resistance, and mechanisms of superconductivity. This drives the current interest in natural materials combining magnetic ordering properties with superconducting properties, such as ruthenium based high temperature copper-oxide superconductors, these called ruthenocuprates. These compounds display an interesting interplay of superconductivity and magnetism. The superconductivity in the Ru-based systems is not destroyed by the presence of ferromagnetic correlations, which contradicts the antagonistic nature of these two phenomena; therefore, these compounds are classified as superconducting ferromagnets. The two main ruthenocuprate systems are RuSr2R2−xCexCu2O10−δ (Ru1222), and RuSr2RCu2O8−δ (Ru1212), where R is Eu, Gd, Sm, and Y. In order to understand how the two mutually exclusive phenomena (superconductivity and magnetism) coexist within a unit cell volume in Ru-based superconducting ferromagnets, it is important to understand their magnetic behaviour. It has been over a decade now that efforts have been devoted to understanding the true nature of magnetic ordering in the Ru1212 and Ru1222 structures. However, up to date no common consensus has been reached. The current understanding of Ru1222 compounds is even more complex. In this thesis, a comprehensive model has been developed to understand the magnetic spin ordering in the Ru1212 and Ru1222 systems, and to establish a cohesive model explaining the temperature as well as field dependent magnetic behaviour of these systems. Different characterization techniques, such as x-ray diffraction, scanning electron microscopy, temperature dependent zero-field cooled and field cooled dc susceptibility, magnetization versus applied field behaviour, detailed field and frequency dependent nonlinear ac susceptibility measurements, resistivity measurements, and neutron powder diffraction were employed to establish a more profound understanding of the magnetism in Ru-based superconducting ferromagnets. Systematic investigations carried out on a series of Ru1222 samples revealed that these compounds always contain additional magnetic phases with their own magnetic behaviour, which is similar to, but yet distinctive from the main Ru1222 phase. The interaction between these two magnetic species affects the physical, magnetic, and transport properties of the material, which can be identifies by (i) the small peak above the Curie temperature (TC ~ 95 K) in the temperature dependent magnetic susceptibility measurements, (ii) the re-entrance of irreversibility in hysteresis loops above TC, which develops a bell-shaped curve in the temperature dependence of the coercive field, and (iii) double-step superconducting transitions. Experimental observation showed that for the pure Ru1222 sample, these features were highly suppressed. A model is proposed, which demonstrates that the superposition of magnetic signals from the two magnetic phases with slightly different magnetic ordering temperatures is responsible for the controversial observations of multiple magnetic transitions in Ru1222 and the features inherent to various magnetic states, such as ferromagnetic, antiferromagnetic, and spin-glass along with coexistence of magnetism and superconductivity. This variety of possible magnetic states has led to the different controversial models proposed in the literature, reflecting one or another feature observed. Further, a detailed investigation was carried out to understand the spin dynamics in the Ru1222 system. The investigation of the nonlinear susceptibility as a function of temperature and applied field suggested that the structural properties as well as the inhomogeneities of the Ru1222 system resulted in the formation of magnetic (ferromagnetic) clusters of different sizes, shapes and properties. The magnetic clustering of the system leads to observation of various features in the dc magnetization and ac susceptibility, consistent with superparamagnetism and cluster spin glass states, which can coexist or stand alone, depending on the temperature range and the strength of the applied field. The formation of a cluster spin glass state by the ferromagnetic clusters suggested that the Ru1222 system does not possess a long range ferromagnetic order, rather short range ferromagnetic order is present in the Ru1222 system. In order to understand the temperature and magnetic field response of the Ru1222 and Ru1212 systems at atomic level, neutron powder diffraction studies (NPD) were carried out on Ru0.9Sr2YCu2.1O7.9 (Ru1212Y) and RuSr2Y1.5Ce0.5Cu2O10−δ (Ru1222Y) samples. NPD measurement showed antiferromagnetic order below TM = 140 K in Ru1212Y sample. A very weak antiferromagnetic signal below 140 K was also observed in Ru1222Y sample, which seems to be due to the presence of Ru1212Y impurity phase. Neutron diffraction measurements under applied fields of 0-6 T showed that with increasing field the AFM order disappeared in both the samples, however, a field-induced ferromagnetic ordering of the Ru moments perpendicular to the c-axis developed for Ru1222Y sample but no field-induced ferromagnetism was observed in Ru1212Y sample

Explanation of magnetic behavior in Ru-based superconducting ferromagnets

We have investigated RuSr2Eu1.5Ce2O10 (Ru-1222) and RuSr2EuCu2O8 (Ru-1212) samples by using x-ray diffraction, scanning electron microscopy, dc magnetization, ac susceptibility, and resistivity measurements. Based on the results obtained, we propose an explanation of the magnetic behaviour of the Ru-based systems. Our model is capable of describing controversial observations of multiple magnetic transitions on temperature dependent dc magnetization measurements as well as the reentrance of irreversibility in hysteresis ≤200K. The experimental results suggest that Ru-based samples always contain a small amount of at least one additional magnetic phase with its own magnetic behaviour which is similar yet distinct from the main Ru phase. The presence of these phases and the superposition of their magnetic contributions can produce different transport properties and lead features that are inherent to various magnetic states, such as ferromagnetic, antiferromagnetic, and spin glass, and still exhibit a coexistence of magnetism and superconductivity at low temperatures. This variety of possible states has led to different controversial models proposed on the literature, reflecting on or another feature observed. The model proposed in this work does not contradict but rather unifies the existing scenarios for the Ru-based systems in common picture