Primary Site Of Damage Research Articles

Glucocorticoids induce a maladaptive epithelial stress response to aggravate acute kidney injury.

Acute kidney injury (AKI) is a frequent and challenging clinical condition associated with high morbidity and mortality and represents a common complication in critically ill patients with COVID-19. In AKI, renal tubular epithelial cells (TECs) are a primary site of damage, and recovery from AKI depends on TEC plasticity. However, the molecular mechanisms underlying adaptation and maladaptation of TECs in AKI remain largely unclear. Here, our study of an autopsy cohort of patients with COVID-19 provided evidence that injury of TECs by myoglobin, released as a consequence of rhabdomyolysis, is a major pathophysiological mechanism for AKI in severe COVID-19. Analyses of human kidney biopsies, mouse models of myoglobinuric and gentamicin-induced AKI, and mouse kidney tubuloids showed that TEC injury resulted in activation of the glucocorticoid receptor by endogenous glucocorticoids, which aggravated tubular damage. The detrimental effect of endogenous glucocorticoids on injured TECs was exacerbated by the administration of a widely clinically used synthetic glucocorticoid, dexamethasone, as indicated by experiments in mouse models of myoglobinuric- and folic acid-induced AKI, human and mouse kidney tubuloids, and human kidney slice cultures. Mechanistically, studies in mouse models of AKI, mouse tubuloids, and human kidney slice cultures demonstrated that glucocorticoid receptor signaling in injured TECs orchestrated a maladaptive transcriptional program to hinder DNA repair, amplify injury-induced DNA double-strand break formation, and dampen mTOR activity and mitochondrial bioenergetics. This study identifies glucocorticoid receptor activation as a mechanism of epithelial maladaptation, which is functionally important for AKI.

Membrane lipid composition of Carnobacterium maltaromaticum CNCM I-3298, a highly cryoresistant lactic bacterium

The growing consumption of fermented products has led to an increasing demand for lactic acid bacteria (LAB), especially for LAB tolerant to freezing/thawing conditions. Carnobacterium maltaromaticum is a psychrotrophic and freeze-thawing resistant lactic acid bacterium. The membrane is the primary site of damage during the cryo-preservation process and requires modulation to improve cryoresistance. However, knowledge about the membrane structure of this LAB genus is limited. We presented here the first study of the membrane lipid composition of C. maltaromaticum CNCM I-3298 including the polar heads and the fatty acid compositions of each lipid family (neutral lipids, glycolipids, phospholipids). The strain CNCM I-3298 is principally composed of glycolipids (32%) and phospholipids (55%). About 95% of glycolipids are dihexaosyldiglycerides while less than 5% are monohexaosyldiglycerides. The disaccharide chain of dihexaosyldiglycerides is composed of α-Gal(1−2)-α-Glc chain, evidenced for the first time in a LAB strain other than Lactobacillus strains. Phosphatidylglycerol is the main phospholipid (94%). All polar lipids are exceptionally rich in C18:1 (from 70% to 80%). Regarding the fatty acid composition, C. maltaromaticum CNCM I-3298 is an atypical bacterium within the genus Carnobacterium due to its high C18:1 proportion but resemble the other Carnobacterium strains as they mostly do not contain cyclic fatty acids.

Amelioration of chilling injury in ‘Guifei’ mango fruit by melatonin is associated with regulation of lipid metabolic enzymes and remodeling of lipidome

The susceptibility of harvested mango fruit to chilling injury (CI) restricts quality preservation. Cell membranes are recognized as primary sites of damage in fruits in response to cold stress, and the maintenance of membrane integrity and function is conducive to alleviating fruit CI. This study aimed to investigate the effects of melatonin (MT), an important bioactive molecule, on cold tolerance in relation to membrane lipid homeostasis in ‘Guifei’ mango fruit during refrigeration. The results showed that application of 0.5 mmol L−1 MT to mango fruit reduced the CI index, discoloration, relative electrolyte leakage (REL) and malondialdehyde (MDA) content while maintaining a higher Fv/Fm value. Reduced activities of phospholipase D (PLD), phospholipase C (PLC) and lipoxygenase (LOX) but increased phospholipase A2 (PLA2) activity were observed in MT-treated fruit compared to control fruit. Furthermore, lipidomic analysis revealed changes in molecular species profiles of various classes of lipids (phospholipids, lysophospholipids, sphingolipids and glycerides) in response to MT. These results indicate that MT could trigger remodeling of lipid molecules by regulating membrane lipid metabolism, which would be conducive to maintaining membrane structure and activating downstream signaling pathways, contributing to improved cold tolerance in mango fruit.

Durability of Digital Flexible Ureteroscope in University Hospital and Ambulatory Surgical Center: Is It Time to Rethink?

Introduction and Objectives: Published literature on damages to a digital flexible ureteroscope (DFU) examines a limited number of ureteroscopes and shows wide variation in its durability. The aim of this study was to compare the primary damage location, causes of DFU damages, and the durability of Karl Storz Flex-Xc digital ureteroscope between University Hospital (UH) and Ambulatory Care Surgery Center (ASC). We also evaluated the available literature on the durability of DFU. Methods: Each damaged DFU prospectively underwent a manufacturer's evaluation to determine the reason for return and primary site of damage. Hospital data on the number of ureteroscopic procedures and damaged DFUs over 3 years were retrospectively reviewed. The possible reason for the damage was classified as either intraoperative or between the procedures. The durability of DFUs, type, and cause of damage were compared between the UH and nonteaching ASC. A chi-square test was utilized for categorical variables. When cell frequencies were <5, Fisher's exact test was used. Results: During the study period, 1211 ureteroscopies were performed and 143 ureteroscopes were returned to the manufacturer. The mean number of uses was 7.45 at the UH and 16.5 at the ASC. The location and cause of damage were similar at both locations. The most common locations of primary damage were at the angle cover (70.6%) and instrument channel (19.2%). Most damage occurred during the handling of the ureteroscopes between surgical procedures (78%). On review of the literature, we found that DFUs were 6 times more durable in a nonteaching hospital. Conclusions: The DFU was more than two times as durable in the ASC as in the UH. Most incidents occurred during handling between surgical procedures. Future research is needed to examine the impact of training and certification of support staff on durability of DFUs.

Are There Different Phenotypes in Geographic Atrophy of AMD? - Pilot Study on Differentiation Using Multimodal Imaging

Geographic atrophy (GA) in patients with age-related macular degeneration (AMD) involves a loss of photoreceptors (PR), retinal pigment epithelium (RPE) and choriocapillaris (CC). For treatment decisions, it is crucial to discern which of these layers the damage originates, subsequently spreading to the others. It has long been thought that the RPE, with its accumulation of lipofuscin, is the site of primary damage in the development of GA. However, histological studies have shown that in some patients, the PR are affected first, followed by secondary damage to the RPE and CC, and in others regression of the CC is the first manifestation. The aim of this study was to use multimodal imaging to determine the extent of the damage at the levels of the PR, RPE and CC, to characterise the individual phenotypic variations of GA and to investigate the corresponding functional impairment. Twenty eyes of 20 patients (mean age 78 years; 14 female, 6 male) with the clinical diagnosis of GA were examined by means of fundus autofluorescence (FAF) to evaluate the damage to the RPE, en face SD-OCT at the level of the PR to characterise the area of cell loss in this layer and OCT angiography (OCT-A, AngioVue, Optovue; 50 µm CC-segmentation with localization below the RPE) to assess regression of the CC. The affected area of each layer was measured. Best-corrected visual acuity (BCVA) test and fundus correlated automated 10° microperimetry (MAIA Microperimetry, CENTERVUE; 4-2 strategy, 68 stimuli) were performed in all patients. The results of these examinations were evaluated and correlated. All eyes showed a different extent of the areas of atrophy in the PR, RPE and CC. The layer with the largest area of atrophy was the RPE in 13 eyes (65%), the PR in 3 eyes (15%) and the CC in 4 eyes (20%). While the visual loss depended entirely on the presence of foveal sparing, microperimetry revealed a correlation between the extent of detectable functional deficit and the largest atrophic area. Multimodal imaging with FAF, en face OCT, OCT-A and a correlation with microperimetry enables a clinical phenotypic differentiation in GA as well as a more precise characterisation of the associated functional impairment. This confirms clinically the histologically demonstrated diversity of the damaged structure (PR, RPE or CC) in patients with GA. However, the variations identified in this pilot study must be confirmed in Reading Center-based larger cohorts. The approach described here may lead to differentiated consideration of the anatomical and functional aspects of the disease and turn out to be helpful in patient selection as well as in identifying and monitoring future therapeutic approaches.

Effect of butylated hydroxytoluene supplementation on ultrastructure of crossbred bovine spermatozoa

The present study was planned to observe the effect of Butylated hydroxytoluene (BHT) on ultra structure changes in bovine crossbred spermatozoa. The sperm plasma membrane is the primary site of damage induced by cryopreservation. There are many harmful conditions such as cold shock, osmotic stress, ice crystal formation or oxidative damage etc which cause sperm cryo-injury and loss of sperm viability and fertility during cryopreservation. At the time of cryopreservation there were considerable ultra structure changes to the acrosomes and middle piece studied by transmission electron microscopy. Semen from two crossbred bulls were collected and extended with egg yolk tris dilutor along with addition of different concentrations of BHT i.e. 0.0mM (Control), 0.5mM (T 1 ) and 1.0mM (T 2 ), respectively. The effect of BHT on ultrastructural alterations was revealed by Transmission electron microscopy during post dilution (Stage I), post equilibration (Stage II) and post thaw (Stage III), respectively. TEM results of spermatozoa at Stage I, II and III showed that major ultrastrucural alterations occur in plasma membrane and outer acrosomal membrane. Group T 1 and T 2 showed significantly lower number of ultrastructural defects compared to control at Stage I, II and III. The study indicated that 1.0mM BHT increases the cryosurvival of sperm as revealed by post thaw lower ultrastructural defects of bovine bull spermatozoa

Sirtuin 5 Regulates Proximal Tubule Fatty Acid Oxidation to Protect against AKI.

The primary site of damage during AKI, proximal tubular epithelial cells, are highly metabolically active, relying on fatty acids to meet their energy demands. These cells are rich in mitochondria and peroxisomes, the two organelles that mediate fatty acid oxidation. Emerging evidence shows that both fatty acid pathways are regulated by reversible posttranslational modifications, particularly by lysine acylation. Sirtuin 5 (Sirt5), which localizes to both mitochondria and peroxisomes, reverses post-translational lysine acylation on several enzymes involved in fatty acid oxidation. However, the role of the Sirt5 in regulating kidney energy metabolism has yet to be determined. We subjected male Sirt5-deficient mice (either +/- or -/-) and wild-type controls, as well as isolated proximal tubule cells, to two different AKI models (ischemia-induced or cisplatin-induced AKI). We assessed kidney function and injury with standard techniques and measured fatty acid oxidation by the catabolism of 14C-labeled palmitate to 14CO2. Sirt5 was highly expressed in proximal tubular epithelial cells. At baseline, Sirt5 knockout (Sirt5-/- ) mice had modestly decreased mitochondrial function but significantly increased fatty acid oxidation, which was localized to the peroxisome. Although no overt kidney phenotype was observed in Sirt5-/- mice, Sirt5-/- mice had significantly improved kidney function and less tissue damage compared with controls after either ischemia-induced or cisplatin-induced AKI. This coincided with higher peroxisomal fatty acid oxidation compared with mitochondria fatty acid oxidation in the Sirt5-/- proximal tubular epithelial cells. Our findings indicate that Sirt5 regulates the balance of mitochondrial versus peroxisomal fatty acid oxidation in proximal tubular epithelial cells to protect against injury in AKI. This novel mechanism might be leveraged for developing AKI therapies.

Molecular Mechanisms of Colistin-Induced Nephrotoxicity

The emergence of multidrug resistant (MDR) infections and the shortage of new therapeutic options have made colistin, a polymyxin antibiotic, the main option for the treatment of MDR Gram-negative bacterial infections in the last decade. However, the rapid onset of renal damage often prevents the achievement of optimal therapeutic doses and/or forces the physicians to interrupt the therapy, increasing the risk of drug resistance. The proper management of colistin-induced nephrotoxicity remains challenging, mostly because the investigation of the cellular and molecular pharmacology of this drug, off the market for decades, has been largely neglected. For years, the renal damage induced by colistin was considered a mere consequence of the detergent activity of this drug on the cell membrane of proximal tubule cells. Lately, it has been proposed that the intracellular accumulation is a precondition for colistin-mediated renal damage, and that mitochondria might be a primary site of damage. Antioxidant approaches (e.g., ascorbic acid) have shown promising results in protecting the kidney of rodents exposed to colistin, yet none of these strategies have yet reached the bedside. Here we provide a critical overview of the possible mechanisms that may contribute to colistin-induced renal damage and the potential protective strategies under investigation.

Multicenter Measurements of T1 Relaxation and Diffusion Tensor Imaging: Intra and Intersite Reproducibility.

Quantitative T1 and diffusion tensor imaging (DTI) may provide information about pathological changes underlying disability and progression in diseases like multiple sclerosis (MS). Imaging the corpus callosum (CC), a primary site of damage in MS with a critical role in interhemispheric connectivity, may be useful for assessing overall brain health, prognosis, and therapy efficacy. We assessed the feasibility of multisite clinical trials using advanced MRI by examining the intra and intersite reproducibility of T1 and DTI measurements in the CC and segmented white matter (WM). Five healthy volunteers were scanned twice within 24 hours at six 3T sites. Coefficients of variation (COVs) and intraclass correlation coefficients (ICCs) for CC and WM T1 , fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (Dax ), and radial diffusivity (Drad ) assessed intrasite and intersite reliability. CC and WM T1 showed excellent intrasite reproducibility with low COVs (mean = .90% and .89%, respectively) and good ICCs (CC = .78, WM = .90). T1 also demonstrated intersite reliability (low COVs: CC = 2.4%, WM = 1.8%; moderate ICCs: CC = .43, WM = .69). DTI had low intrasite COVs (CC: FA = 1.3%, MD = 1.5%, Dax = 1.4%, Drad = 2.2%; WM: FA = .9%, MD = .9%, Dax = .7%, Drad = 1.2%) and high intrasite ICCs (CC: FA = .95, MD = .97, Dax = .94, Drad = .97; CC: FA = .9, MD = .66, Dax = .88, Drad = .63), indicating excellent intrasite reproducibility. DTI also showed excellent intersite reliability with low COVs (CC: FA = 2.1%, MD = 4.1%, Dax = 3.4%, Drad = 5.3%, WM: FA = 1.3%, MD = 1.9%, Dax = 1.8%, Drad = 2.1%,) and good ICCs (CC: FA = .90, MD = .84, Dax = .72, Drad = .90; WM: FA = .83, MD = .34, Dax = .62, Drad = .41). T1 and DTI measures are reproducible using equivalent MRI scanners and sequence protocols. Using a similar MR system, it is feasible to carry out multicenter studies using T1 and DTI to evaluate changes within the CC and WM.

Tortuous Pore Path Through the Glaucomatous Lamina Cribrosa

The lamina cribrosa is a primary site of damage in glaucoma. While mechanical distortion is hypothesized to cause reduction of axoplasmic flow, little is known about how the pores, which contains the retinal ganglion cell axons, traverse the lamina cribrosa. We investigated lamina cribrosa pore paths in vivo to quantify differences in tortuosity of pore paths between healthy and glaucomatous eyes. We imaged 16 healthy, 23 glaucoma suspect and 48 glaucomatous eyes from 70 subjects using a swept source optical coherence tomography system. The lamina cribrosa pores were automatically segmented using a previously described segmentation algorithm. Individual pore paths were automatically tracked through the depth of the lamina cribrosa using custom software. Pore path convergence to the optic nerve center and tortuosity was quantified for each eye. We found that lamina cribrosa pore pathways traverse the lamina cribrosa closer to the optic nerve center along the depth of the lamina cribrosa regardless of disease severity or diagnostic category. In addition, pores of glaucoma eyes take a more tortuous path through the lamina cribrosa compared to those of healthy eyes, suggesting a potential mechanism for reduction of axoplasmic flow in glaucoma.

The wound response in fresh-cut lettuce involves programmed cell death events

In this work, the involvement of programmed cell death (PCD) in the wound-induced postharvest browning disorder and senescence in butterhead lettuce (Lactuca sativa L.) fresh-cuts was studied. At the wounded (cut, bruised) sites, rapid browning, loss of chlorophyll and massive cell death, accompanied with accumulation of reactive oxygen species and increased electrolyte leakage occurred in a narrow strip of tissue adjacent the injury. The dead cell morphology (protoplast and nuclei shrinkage) together with the biochemical and physiological changes resembled necrotic PCD type. With a slight delay post-wounding, senescence associated with similar cell death features was initiated in distant non-wounded sites. In addition to necrotic PCD, both in wounded and senescing tissue, the appearance of empty cell corpses was observed, indicating that part of the cells might undergo vacuolar PCD (self-digestion of cellular content after vacuole collapse). The wounding-induced local cell death at the primary site of damage suggested that PCD may serve as a mechanism to seal-off the wound by building a physical barrier of dead cells. However, the cell death at sites remote from the wound suggests the distribution of long-distance senescence-inducing wound messengers. Trichomes in unwounded tissue often were the first to show H2O2 accumulation and dead cells; thereafter, the elevated H2O2 and cell death appeared in connecting cells and senescence progressed over larger areas. This suggests that trichomes may contribute to mediating the wound signalling leading to subsequent senescence. Our findings demonstrate that PCD is an integral part of the wound syndrome in fresh-cut lettuce.

Vision Loss after Cranial Radiotherapy: Case Report and Review

1.1.Background: The ocular manifestations of various types of radiation vary from patient to patient. As the primary sites of damage are endothelial cells, co-existing microvascular diseases, such as diabetes and hypertension, increase the risk of developing retinopathy and maculopathy from radiation treatment. Prompt recognition of findings and initiation of treatment may delay or decrease associated vision loss. 1.2.Case Report: A 62-year-old male presents to the emergency department complaining of persistent hiccups for three days. Further testing revealed right basal ganglia CNS lymphoma for which he received chemotherapy and external beam radiation. He was referred to the eye clinic from the oncology department with complaints of blurred vision in both eyes. His systemic medical history was remarkable for Insulin Dependent Diabetes Mellitus Type 2 and hypertension. On examination, the visual acuity was 20/40 in each eye. Fundus examination revealed cotton wool spots, macular edema and marked capillary non-perfusion in the posterior poles of both eyes. Over the course of a year, his vision deteriorated to 20/400 in each eye. Considering the patients good control of his underlying microvascular diseases, radiation retinopathy was considered likely etiology for the relatively rapid progression of retinal findings and concurrent worsening of vision. Despite a series of Intravitreal Avastin Injections administered in an attempt to stabilize vision, the patient’s vision was unable to be restored. 1.3.Conclusion: Extensive patient education is imperative for patients undergoing radiation treatment, due to ocular or periocular neoplasms, considering the various possible ocular manifestations. Coexisting microvascular diseases should be taken into consideration as they increase the risk of developing retinopathy. This case report reviews the histopathology, risk factors, natural course and long term sequelae of radiation treatment to familiarize the practicing eye care professional with contemporary evaluation and therapeutic considerations for this potentially vision threatening condition.

Repetitive transcranial magnetic stimulation reduces remote apoptotic cell death and inflammation after focal brain injury

BackgroundAfter focal brain injuries occur, in addition to the effects that are attributable to the primary site of damage, the resulting functional impairments depend highly on changes that occur in regions that are remote but functionally connected to the site of injury. Such effects are associated with apoptotic and inflammatory cascades and are considered to be important predictors of outcome. Repetitive transcranial magnetic stimulation (rTMS) is a noninvasive technique that is used to treat various central nervous system (CNS) pathologies and enhance functional recovery after brain damage.ObjectiveThis study examined the efficacy of rTMS in mitigating remote degeneration and inflammation and in improving functional recovery in a model of focal brain damage.MethodsRats that were undergoing hemicerebellectomy (HCb) were treated with an rTMS protocol for 7 days, and neuronal death indices, glial activation, and functional recovery were assessed.ResultsrTMS significantly reduced neuronal death and glial activation in remote regions and improved functional recovery.ConclusionsOur finding opens up a completely new scenario for exploiting the potential of rTMS as an anti-apoptotic and anti-inflammatory treatment.Electronic supplementary materialThe online version of this article (doi:10.1186/s12974-016-0616-5) contains supplementary material, which is available to authorized users.

Investigating primary sites of damage in photosystem II in response to high temperature

The quick and non-invasive technique of Chlorophyll-a (Chl-a) fluorescence was used to investigate the primary site of damage in photosystem II in response to high temperature stress. Based on the changes observed in several parameters deduced from Chl-a fluorescence curves after giving heat treatment at 40 °C for 2–30 min it was observed that the sequence of events in PS II under heat stress was as follows: inhibition of OEC—decrease in electron donation capacity—increase in thermal dissipation—increase in number of inactive RC—dissociation of LHCII—decrease in the efficiency of primary charge separation, ultimately leading to inhibition of primary photochemistry. Further it was concluded that at 40 °C, the acceptor side of PSII [1–Vj and PHI(Eo)] showed insignificant changes, which indicated that acceptor side of PSII is not a major target site of heat stress.

Cannabinoid CB2 receptor (CB2R) stimulation delays rubrospinal mitochondrial-dependent degeneration and improves functional recovery after spinal cord hemisection by ERK1/2 inactivation.

Spinal cord injury (SCI) is a devastating condition of CNS that often results in severe functional impairments for which there are no restorative therapies. As in other CNS injuries, in addition to the effects that are related to the primary site of damage, these impairments are caused by degeneration of distal regions that are connected functionally to the primary lesion site. Modulation of the endocannabinoid system (ECS) counteracts this neurodegeneration, and pharmacological modulation of type-2 cannabinoid receptor (CB2R) is a promising therapeutic target for several CNS pathologies, including SCI. This study examined the effects of CB2R modulation on the fate of axotomized rubrospinal neurons (RSNs) and functional recovery in a model of spinal cord dorsal hemisection (SCH) at the cervical level in rats. SCH induced CB2R expression, severe atrophy, and cell death in contralateral RSNs. Furthermore, SCH affected molecular changes in the apoptotic cascade in RSNs – increased cytochrome c release, apoptosome formation, and caspase-3 activity. CB2R stimulation by its selective agonist JWH-015 significantly increased the bcl-2/bax ratio, reduced cytochrome c release, delayed atrophy and degeneration, and improved spontaneous functional recovery through ERK1/2 inactivation. These findings implicate the ECS, particularly CB2R, as part of the endogenous neuroprotective response that is triggered after SCI. Thus, CB2R modulation might represent a promising therapeutic target that lacks psychotropic effects and can be used to exploit ECS-based approaches to counteract neuronal degeneration.

Myopia and diabetes mellitus as modificatory factors of glaucomatous optic neuropathy

Myopic deformation of the eye and metabolic alterations of the nerve tissue of patients with diabetes may modify glaucomatous optic neuropathy (GON). Blockage of axonal transport of neurotrophic factors (NTFs) is the event crucial to understanding the factors that affect GON. The primary, but not sole, blockage site is at the lamina cribrosa (LC). Other than this primary site of damage at the LC, 7 other factors may explain atypical nerve fiber layer (NFL) defects and the vulnerability of the nerve fibers in eyes with high myopia and glaucoma: a second point of blockage at the edge of the posterior scleral foramen; ectatic strain on the NFL; ectasia and distortion of the LC; association of a hypoplastic optic disc; thin and weak collagen fibers; peripapillary chorioretinal atrophy; and myopic neuropathy. Among diabetic patients, diabetic neuropathy in the retinal NFL is present initially, and increased resistance to aqueous outflow leads to ocular hypertension. Superimposition of GON on diabetic neuropathy and ocular hypertension in patients with diabetes may enhance their susceptibility to nerve damage. Results of a meta-analysis study suggested a positive association between diabetes mellitus and glaucoma whereas other reports suggested that leakage of vascular endothelial growth factor, a survival mechanism of ischemic neural tissue, and enhanced stiffness of the LC as a result of diabetic glycation may protect neurons from apoptosis. Thus, modification of GON as a result of diabetes remains controversial.

The PsbO homolog from Symbiodinium kawagutii (Dinophyceae) characterized using biochemical and molecular methods

A photosystem II component, the PsbO protein is essential for maximum rates of oxygen production during photosynthesis, and has been extensively characterized in plants and cyanobacteria but not in symbiotic dinoflagellates. Its close interaction with D1 protein has important environmental implications since D1 has been identified as the primary site of damage in endosymbiotic dinoflagellates after thermal stress. We identified and biochemically characterized the PsbO homolog from Symbiodinium kawagutii as a 28-kDa protein, and immunolocalized it to chloroplast membranes. Chloroplast association was further confirmed by western blot on photosynthetic membrane preparations. TX-114 phase partitioning, chromatography, and SDS-PAGE for single band separation and partial peptide sequencing yielded peptides identical or with high identity to PsbO from dinoflagellates. Analysis of a cDNA library revealed three genes differing by only one aminoacid residue in the in silico-translated ORFs despite greater differences at nucleotide level in the untranslated, putative regulatory sequences. The consensus full amino acid sequence displayed all the characteristic domains and features of PsbO from other sources, but changes in functionally critical, highly conserved motifs were detected. Our biochemical, molecular, and immunolocalization data led to the conclusion that the 28-kDa protein from S. kawagutii is the PsbO homolog, thereby named SkPsbO. We discuss the implications of critical amino acid substitutions for a putative regulatory role of this protein.

A study of oxidative stress in gentamicin induced nephrotoxicity and effect of antioxidant vitamin C in Wistar rats.

Background: Gentamicin is very useful aminoglycoside in treatment of gram negative organisms but nephrotoxicity has been a major limiting factor. Various renal pathologies have shown correlation with generation of oxidative stress. So, it was hypothesized that there may be involvement of oxidative stress in gentamicin nephrotoxicity. Aims & Objective: To investigate the role of oxidative stress in gentamicin-induced nephrotoxicity and its prevention by using antioxidant vitamin C in Wistar albino rats. Another objective was to localize the site of kidney damage produced by gentamicin. Materials and Methods: Male Wistar albino rats were administered gentamicin at the dose of 70 mg/kg/day i.m; either alone or in combination with vitamin C. Parameters of oxidative stress like glutathione peroxidase (GPx), glutathione reductase (GR) and total antioxidant status (TAS) were analysed. Renal damage was measured by blood urea and serum creatinine. Histopathological examination of rat kidney was done. The data was subjected to one way ANOVA with post hoc test of significance and the values of P < 0.05 were considered statistically significant. Results: Treatment with gentamicin caused significant reduction of TAS, GPx and GR activity, while blood urea and serum creatinine level were raised significantly as compared to control. Renal damage was confirmed with histopathological studies. The primary site of damage was identified as tubules especially proximal convoluted tubules. Administration of vitamin C alone raised TAS level significantly. Co-administration of vitamin C along with gentamicin led to significant restoration of GPx, GR, TAS, blood urea and serum creatinine level. Conclusion: Renal damage due to gentamicin is associated with oxidative stress. The primary site of damage was renal proximal convoluted tubules. Co-administration of vitamin C along with gentamicin significantly prevented nephrotoxicity by virtue of its antioxidant effect.

CSF-1 signaling mediates recovery from acute kidney injury

Renal tubule epithelia represent the primary site of damage in acute kidney injury (AKI), a process initiated and propagated by the infiltration of macrophages. Here we investigated the role of resident renal macrophages and dendritic cells in recovery from AKI after ischemia/reperfusion (I/R) injury or a novel diphtheria toxin-induced (DT-induced) model of selective proximal tubule injury in mice. DT-induced AKI was characterized by marked renal proximal tubular cell apoptosis. In both models, macrophage/dendritic cell depletion during the recovery phase increased functional and histologic injury and delayed regeneration. After I/R-induced AKI, there was an early increase in renal macrophages derived from circulating inflammatory (M1) monocytes, followed by accumulation of renal macrophages/dendritic cells with a wound-healing (M2) phenotype. In contrast, DT-induced AKI only generated an increase in M2 cells. In both models, increases in M2 cells resulted largely from in situ proliferation in the kidney. Genetic or pharmacologic inhibition of macrophage colony-stimulating factor (CSF-1) signaling blocked macrophage/dendritic cell proliferation, decreased M2 polarization, and inhibited recovery. These findings demonstrated that CSF-1-mediated expansion and polarization of resident renal macrophages/dendritic cells is an important mechanism mediating renal tubule epithelial regeneration after AKI.

Acute doxorubicin insult in the mouse ovary is cell- and follicle-type dependent.

Primary ovarian insufficiency (POI) is one of the many unintended consequences of chemotherapy faced by the growing number of female cancer survivors. While ovarian repercussions of chemotherapy have long been recognized, the acute insult phase and primary sites of damage are not well-studied, hampering efforts to design effective intervention therapies to protect the ovary. Utilizing doxorubicin (DXR) as a model chemotherapy agent, we defined the acute timeline for drug accumulation, induced DNA damage, and subsequent cellular and follicular demise in the mouse ovary. DXR accumulated first in the core ovarian stroma cells, then redistributed outwards into the cortex and follicles in a time-dependent manner, without further increase in total ovarian drug levels after four hours post-injection. Consistent with early drug accumulation and intimate interactions with the blood supply, stroma cell-enriched populations exhibited an earlier DNA damage response (measurable at 2 hours) than granulosa cells (measurable at 4 hours), as quantified by the comet assay. Granulosa cell-enriched populations were more sensitive however, responding with greater levels of DNA damage. The oocyte DNA damage response was delayed, and not measurable above background until 10–12 hours post-DXR injection. By 8 hours post-DXR injection and prior to the oocyte DNA damage response, the number of primary, secondary, and antral follicles exhibiting TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labeling)-positive granulosa cells plateaued, indicating late-stage apoptosis and suggesting damage to the oocytes is subsequent to somatic cell failure. Primordial follicles accumulate significant DXR by 4 hours post-injection, but do not exhibit TUNEL-positive granulosa cells until 48 hours post-injection, indicating delayed demise. Taken together, the data suggest effective intervention therapies designed to protect the ovary from chemotherapy accumulation and induced insult in the ovary must act almost immediately to prevent acute insult as significant damage was seen in stroma cells within the first two hours.