Publications by authors named "Kevorkian R"

Hypothermia in combination with infection presents a complex challenge in clinical and battlefield medicine. Multifaceted physiological and immunological consequences of hypothermia drastically change the risk, progression, and treatment of a concomitant infection. Managing hypothermia and infection in extreme cold settings is particularly relevant in an era with increased risk of military operations in Polar climates.

View Article and Find Full Text PDF

Introduction: Molecular hydrogen is produced by the fermentation of organic matter and consumed by organisms including hydrogenotrophic methanogens and sulfate reducers in anoxic marine sediment. The thermodynamic feasibility of these metabolisms depends strongly on organic matter reactivity and hydrogen concentrations; low organic matter reactivity and high hydrogen concentrations can inhibit fermentation so when organic matter is poor, fermenters might form syntrophies with methanogens and/or sulfate reducers who alleviate thermodynamic stress by keeping hydrogen concentrations low and tightly controlled. However, it is unclear how these metabolisms effect porewater hydrogen concentrations in natural marine sediments of different organic matter reactivities.

View Article and Find Full Text PDF
Article Synopsis
  • The study investigates how the bacteria serovar Typhimurium reacts to different diets (fibrous vs. high-fat) over time in mice, focusing on its metabolic responses and implications for antibiotic resistance.
  • Findings indicate that mice on a high-fat diet showed increased inflammation, affecting gene expression related to respiration and infection phases (early, peak, late), highlighting the bacteria's adaptability.
  • The research suggests that understanding these dietary influences on serovar Typhimurium could lead to new therapeutic strategies to combat infections, especially amid rising antibiotic resistance.
View Article and Find Full Text PDF

Chronic Chagas cardiomyopathy (CCC) has unique pathogenic and clinical features with worse prognosis than other causes of heart failure (HF), despite the fact that patients with CCC are often younger and have fewer comorbidities. Patients with CCC were not adequately represented in any of the landmark HF studies that support current treatment guidelines. PARACHUTE-HF (Prevention And Reduction of Adverse outcomes in Chagasic Heart failUre Trial Evaluation) is an active-controlled, randomized, phase IV trial designed to evaluate the effect of sacubitril/valsartan 200 mg twice daily vs enalapril 10 mg twice daily added to standard of care treatment for HF.

View Article and Find Full Text PDF
Article Synopsis
  • The research investigates how the serovar Typhimurium bacterium adapts its metabolic response to different diets, specifically fibrous versus high-fat, over time, which is crucial for developing new treatments for infections amid increasing antibiotic resistance.
  • A multi-omics approach was used in mice, revealing that the high-fat diet led to increased inflammation and distinct phases of infection based on gene expression, including genes linked to how the bacteria enter host cells.
  • The findings underscore the importance of understanding pathogen responses to dietary changes, suggesting potential targets for therapies to combat infections linked to shifts toward high-fat, low-fiber diets.
View Article and Find Full Text PDF
Article Synopsis
  • The study details the genome of a lytic phage called EAb13, which was isolated from sewage and is effective against multidrug-resistant bacteria.
  • EAb13 is categorized as an unclassified siphovirus, which are a type of virus that typically have long, flexible tails.
  • Its genome is 82,411 base pairs long, contains 40.15% GC content, includes 126 protein-coding sequences, has 1 tRNA, and features direct terminal repeats that are 2,177 base pairs long.
View Article and Find Full Text PDF

We describe the genome of a lytic phage, ESa2, isolated from environmental water and specific for Staphylococcus aureus. ESa2 belongs to the family and genus . Its genome consists of 141,828 bp, with 30.

View Article and Find Full Text PDF

Marine deep subsurface sediment is often a microbial environment under energy-limited conditions. However, microbial life has been found to persist and even thrive in deep subsurface environments. The Mariana forearc represents an ideal location for determining how microbial life can withstand extreme conditions including pH 10-12.

View Article and Find Full Text PDF

Shigellosis is a leading global cause of diarrheal disease and travelers' diarrhea now being complicated by the dissemination of antibiotic resistance, necessitating the development of alternative antibacterials such as therapeutic bacteriophages (phages). Phages with lytic activity against strains were isolated from sewage. The genomes of 32 phages were sequenced, and based on genomic comparisons belong to seven taxonomic genera: , , , , , and .

View Article and Find Full Text PDF

As marine sediments are buried, microbial communities transition from sulfate-reduction to methane-production after sulfate is depleted. When this biogenic methane diffuses into the overlying sulfate-rich sediments, it forms a sulfate-methane transition zone (SMTZ) because sulfate reducers deplete hydrogen concentrations and make hydrogenotrophic methanogenesis exergonic in the reverse direction, a process called the anaerobic oxidation of methane (AOM). Microbial participation in these processes is often inferred from geochemistry, genes, and gene expression changes with sediment depth, using sedimentation rates to convert depth to time.

View Article and Find Full Text PDF

ANME-1 archaea subsist on the very low energy of anaerobic oxidation of methane (AOM). Most marine sediments shift from net AOM in the sulfate methane transition zone (SMTZ) to methanogenesis in the methane zone (MZ) below it. In White Oak River estuarine sediments, ANME-1 comprised 99.

View Article and Find Full Text PDF

Global marine sediments harbor a large and highly diverse microbial biosphere, but the mechanism by which this biosphere is established during sediment burial is largely unknown. During burial in marine sediments, concentrations of easily metabolized organic compounds and total microbial cell abundance decrease. However, it is unknown whether some microbial clades increase with depth.

View Article and Find Full Text PDF

The subduction of seamounts and ridge features at convergent plate boundaries plays an important role in the deformation of the overriding plate and influences geochemical cycling and associated biological processes. Active serpentinization of forearc mantle and serpentinite mud volcanism on the Mariana forearc (between the trench and active volcanic arc) provides windows on subduction processes.  Here, we present (1) the first observation of an extensive exposure of an undeformed Cretaceous seamount currently being subducted at the Mariana Trench inner slope; (2) vertical deformation of the forearc region related to subduction of Pacific Plate seamounts and thickened crust; (3) recovered Ocean Drilling Program and International Ocean Discovery Program cores of serpentinite mudflows that confirm exhumation of various Pacific Plate lithologies, including subducted reef limestone; (4) petrologic, geochemical and paleontological data from the cores that show that Pacific Plate seamount exhumation covers greater spatial and temporal extents; (5) the inference that microbial communities associated with serpentinite mud volcanism may also be exhumed from the subducted plate seafloor and/or seamounts; and (6) the implications for effects of these processes with regard to evolution of life.

View Article and Find Full Text PDF

Anoxic subsurface sediments contain communities of heterotrophic microorganisms that metabolize organic carbon at extraordinarily low rates. In order to assess the mechanisms by which subsurface microorganisms access detrital sedimentary organic matter, we measured kinetics of a range of extracellular peptidases in anoxic sediments of the White Oak River Estuary, NC. Nine distinct peptidase substrates were enzymatically hydrolyzed at all depths.

View Article and Find Full Text PDF
Article Synopsis
  • Difficulty in quantifying significant microbes in marine sediments affects our understanding of their interactions and niches.
  • An incubation study revealed a decline in sulfate and an increase in methane along with specific population turnover times for uncultured clades under anoxic conditions.
  • The findings suggest that only a limited number of microbial groups, particularly those involved in methanogenesis, increased during the transition from sulfate reduction to methanogenesis, with measurable turnover times ranging from approximately 9 to 14 days.
View Article and Find Full Text PDF

There is no universally accepted method to quantify bacteria and archaea in seawater and marine sediments, and different methods have produced conflicting results with the same samples. To identify best practices, we compiled data from 65 studies, plus our own measurements, in which bacteria and archaea were quantified with fluorescent in situ hybridization (FISH), catalyzed reporter deposition FISH (CARD-FISH), polyribonucleotide FISH, or quantitative PCR (qPCR). To estimate efficiency, we defined "yield" to be the sum of bacteria and archaea counted by these techniques divided by the total number of cells.

View Article and Find Full Text PDF

Testosterone regulates energy metabolism and skeletal muscle mass in males, but the molecular mechanisms are not fully understood. This study investigated the response of skeletal muscle to castration and testosterone replacement in 8-week-old male mice. Using microarray analyses of mRNA levels in gastrocnemius muscle, 91 genes were found to be negatively regulated by testosterone and 68 genes were positively regulated.

View Article and Find Full Text PDF

Purpose: To assess the safety data from two large, multicenter, phase 2 trials on the use of gadoversetamide (OptiMARK, Tyco Healthcare/Mallinckrodt, St. Louis, MO) as a contrast agent in delayed hyperenhancement magnetic resonance imaging (DE-MRI) in patients with acute and chronic myocardial infarction (MI).

Materials And Methods: The study population from both trials comprised 577 patients who were randomly assigned to one of four dose groups (0.

View Article and Find Full Text PDF
Andropause.

Mo Med

May 2007

Andropause is a common part of aging in older men that affects a multitude of health parameters. It is imperative that male hypogonadism be evaluated and treated with hormonal replacement to avoid the development of frailty and effects on sexual health. This article will review the diagnosis and management of andropause.

View Article and Find Full Text PDF

Frailty occurs in aging males for a variety of reasons. It is less common in males than females. Diseases which are particularly associated with frailty are diabetes mellitus, atherosclerosis, anemia and chronic obstructive pulmonary disease.

View Article and Find Full Text PDF

Three questionnaires, the St. Louis University Androgen Deficiency in Aging Male (ADAM), the Aging Male Survey (AMS) and the Massachusetts Male Aging Study (MMAS), have been developed as potential screening tools for hypogonadism in older males. We compared these questionnaires in 148 males aged 23-80 years using bioavailable testosterone as the "biochemical gold standard" for diagnosis of hypogonadism.

View Article and Find Full Text PDF

Testosterone levels decline over the lifespan. Many symptoms of hypogonadism are similar to age-related changes in older males. A small number of studies have suggested that some of these symptoms may be reversed by testosterone.

View Article and Find Full Text PDF