Abiotrophia defectiva Endocarditis Complicated by Stroke and Spinal Osteomyelitis.

A 67-year-old male with coronary artery disease and aortic stenosis after coronary artery bypass graft (CABG) and aortic valve replacement (AVR) presented after a two-day history of dizziness and frequent falls. Initially, he was found to have a subacute infarct of the left temporal lobe, osteomyelitis of the lumbar spine, and an aortic valve vegetation. Further investigations demonstrated gram-positive bacteremia, and, eventually, the causative organism was identified as Abiotrophia defectiva. He was treated with penicillin and gentamicin in the inpatient setting and then discharged with outpatient intravenous (IV) ceftriaxone for the remainder of the four-week antibiotic course. He did not suffer complications after initiating therapy and recovered. We wish to raise awareness of the existence and complications that can result from A. defectiva endocarditis and encourage further research into effective antibiotic treatment. A. defectiva endocarditis may lead to neurological and orthopedic infective sequelae; understanding and awareness of Abiotrophia spp. infections are important to ensure effective treatment of endocarditis.

Metformin-Associated Lactic Acidosis: A Case Report.

Introduction: Metformin is considered a first-line therapy for patients with diabetes secondary to its cost efficiency, minimal side effects, and marked improvement in one's hemoglobin A1c; however, metformin is avoided in patients with renal insufficiency out of concern for drug accumulation and lactic acidosis. In fact, there is a black box warning for metformin, identifying lactic acidosis as the inciting trigger for fatal arrhythmias and death. Case Presentation: A 62-year-old male presented with multiple episodes of nausea, vomiting, abdominal pain, and decreased urine output for 3 days after working on a roof, all day in the summer heat. He did not drink more than a bottle of water throughout that day and noted that afterward, he seemed to have little to no urine output. At presentation, he was in moderate distress due to abdominal pain and was diaphoretic, tachypneic, and hypertensive. The patient was given dextrose and started on a sodium bicarbonate drip. He was also given calcium gluconate. His mentation and respiratory status continued to decline throughout that day, and he required intubation and mechanical ventilation. The patient ultimately recovered quite rapidly upon receiving hemodialysis. Conclusion: This case report shows the critical nature of identifying and quickly treating metformin toxicity.

Left Atrial Myxoma With Aortic Insufficiency Leading to Cerebrovascular Accident.

Primary cardiac tumors are extremely rare and can lead to significant neurologic symptoms if not diagnosed and treated appropriately. Cardiac myxomas represent the most common subtype of cardiac tumors and are typically located on the left side of the heart and, when diagnosed appropriately with echocardiography, are typically treated with surgical excision. Simultaneous presentation of myxoma and valvular insufficiency is rare and under-documented. This is a rare case of a patient with a left atrial myxoma and aortic insufficiency leading to cerebrovascular symptoms.

Lazarus Syndrome After Aortic Aneurysm Repair.

Introduction: Lazarus syndrome is defined as the spontaneous return of circulation after cessation of cardiopulmonary resuscitation (CPR). Though there have been multiple cases of Lazarus syndrome documented in the literature, it is a significantly underreported phenomenon with less than 100 cases reported in the literature since the first case in 1982. Case Presentation: After elective aortic aneurysm repair, an 88-year-old with a do-not-resuscitate directive had cardiac arrest, briefly showing post-mortem respiration and pulse. Despite resuscitation efforts including pharmacological intervention and CPR, he passed away within an hour. This case highlights complexities in end-of-life care and warrants exploration of post-mortem physiological responses. Conclusion: The Lazarus phenomenon, rare post-CPR circulation return, challenges resuscitation cessation. Our case, among the oldest, highlights extended monitoring necessity, especially in chronic obstructive pulmonary disease patients. Debate persists on monitoring duration after failed CPR, lacking established Lazarus syndrome prevention guidelines.

Ascorbic acid modulation of iron homeostasis and lysosomal function in trabecular meshwork cells.

PURPOSE: To investigate the antioxidant properties and biological functions of ascorbic acid (AA) on trabecular meshwork (TM) cells. METHODS: Primary cultures of porcine TM cells were supplemented for 10 days with increasing concentrations of AA. Antioxidant properties against cytotoxic effect of H2O2 were evaluated by monitoring cell viability. Redox-active iron was quantified using calcein-AM. Intracellular reactive oxygen species (iROS) production was quantified using H2DCFDA. Ferritin and cathepsin protein levels were analyzed by Western blot. Autophagy was evaluated by monitoring lipidation of LC3-I to LC3-II. Lysosomal proteolysis and cathepsins activities were quantified using specific fluorogenic substrates. RESULTS: AA exerts a dual effect against oxidative stress in TM cells, acting as an anti-oxidant or a pro-oxidant, depending on the concentration used. The pro-oxidant effect of AA was mediated by free intracellular iron and correlated with increased protein levels of ferritin and elevated iROS. In contrast, antioxidant properties correlated with lower ferritin and basal iROS content. Ascorbic acid supplementation also caused induction of autophagy, as well as increased lysosomal proteolysis, with the latter resulting from higher proteolytic activation of lysosomal cathepsins in treated cultures. CONCLUSIONS: Our results suggest that the reported decrease of AA levels in plasma and aqueous humor can compromise lysosomal degradation in the outflow pathway cells with aging and contribute to the pathogenesis of glaucoma. Restoration of physiological levels of vitamin C inside the cells might improve their ability to degrade proteins within the lysosomal compartment and recover tissue function.

Cathepsin B is up-regulated and mediates extracellular matrix degradation in trabecular meshwork cells following phagocytic challenge.

Cells in the trabecular meshwork (TM), a tissue responsible for draining aqueous humor out of the eye, are known to be highly phagocytic. Phagocytic activity in TM cells is thought to play an important role in outflow pathway physiology. However, the molecular mechanisms triggered by phagocytosis in TM cells are unknown. Here we investigated the effects of chronic phagocytic stress on lysosomal function using different phagocytic ligands (E. coli, carboxylated beads, collagen I-coated beads, and pigment). Lysotracker red co-localization and electron micrographs showed the maturation of E. coli- and collagen I-coated beads-containing phagosomes into phagolysosomes. Maturation of phagosomes into phagolysosomes was not observed with carboxylated beads or pigment particles. In addition, phagocytosis of E. coli and collagen I-coated beads led to increased lysosomal mass, and the specific up-regulation and activity of cathepsin B (CTSB). Higher levels of membrane-bound and secreted CTSB were also detected. Moreover, in vivo zymography showed the intralysosomal degradation of ECM components associated with active CTSB, as well as an overall increased gelatinolytic activity in phagocytically challenged TM cells. This increased gelatinolytic activity with phagocytosis was partially blocked with an intracellular CTSB inhibitor. Altogether, these results suggest a potential role of phagocytosis in outflow pathway tissue homeostasis through the up-regulation and/or proteolytic activation of extracellular matrix remodeling genes.

Lysosomal basification and decreased autophagic flux in oxidatively stressed trabecular meshwork cells: implications for glaucoma pathogenesis.

Increasing evidence suggests oxidative damage as a key factor contributing to the failure of the conventional outflow pathway tissue to maintain appropriate levels of intraocular pressure, and thus increase the risk for developing glaucoma, a late-onset disease which is the second leading cause of permanent blindness worldwide. Autophagy is emerging as an essential cellular survival mechanism against a variety of stressors, including oxidative stress. Here, we have monitored, by using different methodologies (LC3-I to LC3-II turnover, tfLC3, and Cyto ID), the induction of autophagy and autophagy flux in TM cells subjected to a normobaric hyperoxic model of mild chronic oxidative stress. Our data indicate the MTOR-mediated activation of autophagy and nuclear translocation of TFEB in oxidatively stressed TM cells, as well as the role of autophagy in the occurrence of SA-GLB1/SA-ß-gal. Concomitant with the activation of the autophagic pathway, TM cells grown under oxidative stress conditions displayed, however, reduced cathepsin (CTS) activities, reduced lysosomal acidification and impaired CTSB proteolytic maturation, resulting in decreased autophagic flux. We propose that diminished autophagic flux induced by oxidative stress might represent one of the factors leading to progressive failure of cellular TM function with age and contribute to the pathogenesis of primary open angle glaucoma.

Intralysosomal iron induces lysosomal membrane permeabilization and cathepsin D-mediated cell death in trabecular meshwork cells exposed to oxidative stress.

PURPOSE: To investigate the role of intralysosomal redox-active iron in oxidative stress-induced damage in trabecular meshwork (TM) cells. METHODS: Chronic oxidative stress was applied using the hyperoxic model; acute oxidative stress was applied with H(2)O(2). Microarray analysis was performed using microarrays. mRNA and protein levels were quantified by real-time PCR and Western blot analysis, respectively. Redox-active iron was monitored using calcein-AM. Apoptosis was quantified using double staining. DNA damage was evaluated by single-cell gel electrophoresis assay. Lysosomal permeabilization was monitored using uptake and acridine orange relocation techniques. Intracellular ROS production was quantified using H(2)DCFDA. Cytosolic translocation of cathepsins was visualized with pepstatin-A-BODIPY-FL. Chemical inhibition of cathepsins was achieved with leupeptin and pepstatin A. Silencing of cathepsin expression was accomplished with miRNA sequences. Lysosomal iron chelation was achieved with desferrioxamine. RESULTS: Chronically stressed TM cells showed elevated levels of redox-active iron and altered expression of genes involved in intracellular iron homeostasis. Although iron increased ROS production and lipofuscin levels and sensitized TM cells to H(2)O(2), intralysosomal iron chelation completely protected the cells against H(2)O(2)-induced cell death and apoptosis. The protective effect of desferrioxamine was mediated by the prevention of lysosomal ROS generation and the rupture of lysosomal membrane, with the subsequent release of cathepsin D into the cytosol. CONCLUSIONS: These results indicate that the generation of intralysosomal ROS induces lysosomal membrane permeabilization and the release of cathepsin D into the cytosol, leading to TM cell death. Here, the authors propose a mechanism by which oxidative stress might contribute to the decrease in cellularity reported in the TM tissue with both aging and disease.

Potential role of lysosomal dysfunction in the pathogenesis of primary open angle glaucoma.

Primary open angle glaucoma (POAG) is a late onset disease usually accompanied by elevated intraocular pressure (IOP) that results from the failure of the trabecular meshwork (TM) to maintain normal levels of aqueous humor outflow resistance. Cells in the TM are subjected to chronic oxidative stress through reactive oxygen species (ROS) present in the aqueous humor (AH) and generated by normal metabolism. Exposure to ROS is thought to contribute to the morphological and physiological alterations of the outflow pathway in aging and POAG. Our results indicate that chronic exposure of TM cells to oxidative stress causes the accumulation of nondegradable material within the lysosomal compartment leading to diminished lysosomal activity and increased SA-beta-Gal expression. Because the lysosomal compartment is responsible for maintaining general cellular turnover, such impaired activity may lead to a progressive cellular decline in the TM cell function and thus contribute to the progression of POAG.

Cultured porcine trabecular meshwork cells display altered lysosomal function when subjected to chronic oxidative stress.

PURPOSE: To investigate the effects of chronic oxidative stress on lysosomal function in trabecular meshwork (TM) cells. METHODS: Confluent cultures of porcine TM cells were grown for 2 weeks in physiological (5% O(2)) or hyperoxic conditions (40% O(2)) in the presence or absence of the protease inhibitor leupeptin (10 microM). The following parameters were quantified using the fluorogenic probes indicated within parentheses: autofluorescence, intracellular reactive oxygen species (ROS; H(2)DCFDA), mitochondrial membrane potential (JC-1), mitochondrial content (Mitotracker Red; Invitrogen-Molecular Probes, Eugene, OR), lysosomal content (acridine orange and Lysotracker Red [Invitrogen-Molecular Probes]), autophagic vacuole content (MDC), SA-beta-galactosidase (FDG), and cathepsin activities (z-FR-AMC). Cathepsin levels were quantified by qPCR and Western blot analysis. Ultrastructural analysis was performed by transmission electron microscopy. RESULTS: Prolonged exposure of porcine TM cells to a hyperoxic environment led to an increase in ROS production and oxidized material. Electron micrographs revealed the cytoplasmic accumulation of lipofuscin-loaded lysosomes. Augmented lysosomal and autophagic vacuole content was confirmed with specific fluorophores. The mRNA and protein levels of several cathepsins were upregulated with oxidative stress. This upregulated expression did not correlate with increased lysosomal activity. CONCLUSIONS: The results indicate that chronic exposure of TM cells to oxidative stress causes the accumulation of nondegradable material within the lysosomal compartment, leading to diminished lysosomal activity. Since the lysosomal system is responsible for the continuous turnover of cellular organelles, impaired lysosomal activity may lead to progressive failure of cellular TM function with age.