scholarly journals Once-daily gentamicin therapy for experimental Escherichia coli meningitis.

1997 ◽  
Vol 41 (1) ◽  
pp. 49-53 ◽  
Author(s):  
A Ahmed ◽  
M M París ◽  
M Trujillo ◽  
S M Hickey ◽  
L Wubbel ◽  
...  
Keyword(s):  
In Vivo Studies ◽  
Bacterial Killing ◽  
Once Daily ◽  
E Coli ◽  
Aminoglycoside Therapy ◽  
Gentamicin Concentration ◽  
Gentamicin Therapy ◽  
The Impact

In vitro and in vivo studies have demonstrated that the bacteriologic efficacy of once-daily aminoglycoside therapy is equivalent to that achieved with conventional multiple daily dosing. The impact of once-daily dosing for meningitis has not been studied. Using the well-characterized rabbit meningitis model, we compared two regimens of the same daily dosage of gentamicin given either once or in three divided doses for 24 or 72 h. The initial 1 h mean cerebrospinal fluid (CSF) gentamicin concentration for animals receiving a single dose (2.9 +/- 1.7 micrograms/ml) was threefold higher than that for the animals receiving multiple doses. The rate of bacterial killing in the first 8 h of treatment was significantly greater for the animals with higher concentrations in their CSF (-0.21 +/- 0.19 versus -0.03 +/- 0.22 log10 CFU/ml/h), suggesting concentration-dependent killing. By 24h, the mean reduction in bacterial titers was similar for the two regimens. In animals treated for 72 h, no differences in bactericidal activity was noted for 24, 48, or 72 h. Gentamicin at two different dosages was administered intracisternally to a separate set of animals to achieve considerably higher CSF gentamicin concentrations. In these animals, the rate of bacterial clearance in the first 8 h (0.52 +/- 0.15 and 0.58 +/- 0.15 log10 CFU/ml/h for the lower and higher dosages, respectively) was significantly greater than that in animals treated intravenously. In conclusion, there is evidence of concentration-dependent killing with gentamicin early in treatment for experimental E. coli meningitis, and once-daily dosing therapy appears to be at least as effective as multiple-dose therapy in reducing bacterial counts in CSF.

scholarly journals Once-versus thrice-daily netilmicin combined with amoxicillin, penicillin, or vancomycin against Enterococcus faecalis in a pharmacodynamic in vitro model.

1996 ◽  
Vol 40 (10) ◽  
pp. 2258-2261 ◽  
Author(s):  
S Schwank ◽  
J Blaser
Keyword(s):  
Enterococcus Faecalis ◽  
Half Life ◽  
In Vitro Model ◽  
Bacterial Biofilm ◽  
In Vivo Studies ◽  
Bacterial Killing ◽  
Once Daily ◽  
Vitro Model

Several in vitro and in vivo studies as well as clinical trials have demonstrated that once-daily aminoglycoside regimens are as effective as or more effective than multiple daily dosings. However, the most favorable aminoglycoside dosing regimen for treating enterococcal endocarditis remains controversial. The same total dose of netilmicin was administered as once-daily (24-micrograms/ml peaks) and thrice-daily (8 micrograms/ml) regimens in a pharmacodynamic in vitro model simulating exposure of Enterococcus faecalis to human serum kinetics. Netilmicin was administered in combination with continuous infusions of amoxicillin, vancomycin, or penicillin against a bacterial biofilm adhering to glass beads. No significant differences in bacterial killing were found after 24 or 48 h between the once- and thrice-daily regimens. Additional experiments considering animal kinetics (half-life of netilmicin, 20 min) instead of human kinetics (half-life, 2.5 h) in the pharmacodynamic model also revealed similar results. The addition of netilmicin synergistically increased the activity of vancomycin (P < 0.05). In contrast, amoxicillin alone was as effective as the combination with netilmicin. Thus, it could not be established in this model that once-daily dosing of aminoglycosides is contraindicated for treating infections caused by E. faecalis.

scholarly journals Effects of Bacterial CLPB Protein Fragments on Food Intake and PYY Secretion

Nutrients ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 2223
Author(s):  
Manon Dominique ◽  
Nicolas Lucas ◽  
Romain Legrand ◽  
Illona-Marie Bouleté ◽  
Christine Bôle-Feysot ◽  
...  
Keyword(s):  
Food Intake ◽  
Peptide Yy ◽  
Molecular Mimicry ◽  
Potential Effect ◽  
In Vivo Studies ◽  
Sprague Dawley ◽  
E Coli ◽  
In Vivo Effects

CLPB (Caseinolytic peptidase B) protein is a conformational mimetic of α-MSH, an anorectic hormone. Previous in vivo studies have already shown the potential effect of CLPB protein on food intake and on the production of peptide YY (PYY) by injection of E. coli wild type (WT) or E. coli ΔClpB. However, until now, no study has shown its direct effect on food intake. Furthermore, this protein can fragment naturally. Therefore, the aim of this study was (i) to evaluate the in vitro effects of CLPB fragments on PYY production; and (ii) to test the in vivo effects of a CLPB fragment sharing molecular mimicry with α-MSH (CLPB25) compared to natural fragments of the CLPB protein (CLPB96). To do that, a primary culture of intestinal mucosal cells from male Sprague–Dawley rats was incubated with proteins extracted from E. coli WT and ΔCLPB after fragmentation with trypsin or after a heat treatment of the CLPB protein. PYY secretion was measured by ELISA. CLPB fragments were analyzed by Western Blot using anti-α-MSH antibodies. In vivo effects of the CLPB protein on food intake were evaluated by intraperitoneal injections in male C57Bl/6 and ob/ob mice using the BioDAQ® system. The natural CLPB96 fragmentation increased PYY production in vitro and significantly decreased cumulative food intake from 2 h in C57Bl/6 and ob/ob mice on the contrary to CLPB25. Therefore, the anorexigenic effect of CLPB is likely the consequence of enhanced PYY secretion.

67 Current Status and Future Prospective of the Use of Plant Bioactive Compounds in Dairy and Beef Cattle

2021 ◽  
Vol 99 (Supplement_1) ◽  
pp. 132-132
Author(s):  
Sergio Calsamiglia ◽  
Maria Rodriguez-Prado ◽  
Gonzalo Fernandez-Turren ◽  
Lorena Castillejos
Keyword(s):  
Beef Cattle ◽  
Essential Oils ◽  
Average Daily Gain ◽  
Rumen Fermentation ◽  
Production Performance ◽  
In Vivo Studies ◽  
Current Status ◽  
The Impact

Abstract In the last 20 years there has been extensive in vitro research on the effects of plant extracts and essential oils on rumen microbial fermentation. The main objectives have been to improve energy metabolism through a reduction in methane emissions and an increase in propionate production; and to improve protein metabolism by reducing proteolysis and deamination. While the positive results from in vitro studies has stimulated the release of commercial products based on blends of essential oils, there is limited in vivo evidence on the rumen fermentation and production performance effects. A literature search was conducted to select in vivo studies where information on rumen fermentation and animal performance was reported. For dairy cattle, we identified 37 studies of which 21 were adequate to test production performance. Ten studies reported increases and 3 decreases in milk yield. For beef cattle, we identified 20 studies with rumen fermentation profile and 22 with performance data. Average daily gain improved in 7 and decreased in 1 study. Only 1 out of 16 studies reported an improvement in feed efficiency. Data indicate that out of more than 500 products tested in vitro, only around 20 have been tested in vivo in different mixtures and doses. The use of statistical approaches will allow to describe the conditions, doses and responses in dairy and beef cattle performance. The search for postruminal effects offers another alternative use. Evidence for effects on the intestinal and systemic effects on the immune system and antioxidant status (i.e., capsicum, garlic, eugenol, cinnamaldehyde curcuma, catechins, anethol or pinene), and in the modulation of metabolic regulation (capsicum, cinnamaldehyde, curcuma or garlic) may open the opportunity for future applications. However, stability of the product in the GI tract, description of the mechanisms of action and the impact of these changes on performance needs to be further demonstrated.

scholarly journals Impact of the Order of Initiation of Fluconazole and Amphotericin B in Sequential or Combination Therapy on Killing of Candida albicans In Vitro and in a Rabbit Model of Endocarditis and Pyelonephritis

2001 ◽  
Vol 45 (2) ◽  
pp. 485-494 ◽  
Author(s):  
Arnold Louie ◽  
Pamela Kaw ◽  
Partha Banerjee ◽  
Weiguo Liu ◽  
George Chen ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Amphotericin B ◽  
Induced Resistance ◽  
Rabbit Model ◽  
In Vivo Studies ◽  
Infection Model ◽  
Simultaneous Exposure ◽  
The Impact

ABSTRACT In vitro time-kill studies and a rabbit model of endocarditis and pyelonephritis were used to define the impact that the order of exposure of Candida albicans to fluconazole (FLC) and amphotericin B (AMB), as sequential and combination therapies, had on the susceptibility of C. albicans to AMB and on the outcome. The contribution of FLC-induced resistance to AMB for C. albicans also was assessed. In vitro, AMB monotherapy rapidly killed each of four C. albicans strains; FLC alone was fungistatic. Preincubation of these fungi with FLC for 18 h prior to exposure to AMB decreased their susceptibilities to AMB for 8 to >40 h. Induced resistance to AMB was transient, but the duration of resistance increased with the length of FLC preincubation. Yeast sequentially incubated with FLC followed by AMB plus FLC (FLC→AMB+FLC) showed fungistatic growth kinetics similar to that of fungi that were exposed to FLC alone. This antagonistic effect persisted for at least 24 h. Simultaneous exposure of C. albicans to AMB and FLC [AMB+FLC(simult)] demonstrated activity similar to that with AMB alone for AMB concentrations of ≥1 μg/ml; antagonism was seen using an AMB concentration of 0.5 μg/ml. The in vitro findings accurately predicted outcomes in our rabbit infection model. In vivo, AMB monotherapy and treatment with AMB for 24 h followed by AMB plus FLC (AMB→AMB+FLC) rapidly sterilized kidneys and cardiac vegetations. AMB+FLC(simult) and FLC→AMB treatments were slower in clearing fungi from infected tissues. FLC monotherapy and FLC→AMB+FLC were both fungistatic and were the least active regimens. No adverse interaction was observed between AMB and FLC for the AMB→FLC regimen. However, FLC→AMB treatment was slower than AMB alone in clearing fungi from tissues. Thus, our in vitro and in vivo studies both demonstrate that preexposure of C. albicans to FLC reduces fungal susceptibility to AMB. The length of FLC preexposure and whether AMB is subsequently used alone or in combination with FLC determine the duration of induced resistance to AMB.

scholarly journals Role of Hyaluronan in Human Adipogenesis: Evidence from in-Vitro and in-Vivo Studies

2019 ◽  
Vol 20 (11) ◽  
pp. 2675 ◽  
Author(s):  
Nicholas Wilson ◽  
Robert Steadman ◽  
Ilaria Muller ◽  
Mohd Draman ◽  
D. Aled Rees ◽  
...  
Keyword(s):  
Stem Cell Differentiation ◽  
In Vivo Studies ◽  
Peroxisome Proliferator ◽  
Synthesis Inhibitor ◽  
Peroxisome Proliferator Activated Receptor ◽  
Inhibitory Role ◽  
The Impact

Hyaluronan (HA), an extra-cellular matrix glycosaminoglycan, may play a role in mesenchymal stem cell differentiation to fat but results using murine models and cell lines are conflicting. Our previous data, illustrating decreased HA production during human adipogenesis, suggested an inhibitory role. We have investigated the role of HA in adipogenesis and fat accumulation using human primary subcutaneous preadipocyte/fibroblasts (PFs, n = 12) and subjects of varying body mass index (BMI). The impact of HA on peroxisome proliferator-activated receptor gamma (PPARγ) expression was analysed following siRNA knockdown or HA synthase (HAS)1 and HAS2 overexpression. PFs were cultured in complete or adipogenic medium (ADM) with/without 4-methylumbelliferone (4-MU = HA synthesis inhibitor). Adipogenesis was evaluated using oil red O (ORO), counting adipogenic foci, and measurement of a terminal differentiation marker. Modulating HA production by HAS2 knockdown or overexpression increased (16%, p < 0.04) or decreased (30%, p = 0.01) PPARγ transcripts respectively. The inhibition of HA by 4-MU significantly enhanced ADM-induced adipogenesis with 1.52 ± 0.18- (ORO), 4.09 ± 0.63- (foci) and 2.6 ± 0.21-(marker)-fold increases compared with the controls, also increased PPARγ protein expression (40%, (p < 0.04)). In human subjects, circulating HA correlated negatively with BMI and triglycerides (r = −0.396 (p = 0.002), r = −0.269 (p = 0.038), respectively), confirming an inhibitory role of HA in human adipogenesis. Thus, enhancing HA action may provide a therapeutic target in obesity.

scholarly journals Exposure to airborne gold nanoparticles: a review of current toxicological data on the respiratory tract

2020 ◽  
Vol 22 (8) ◽  
Author(s):  
Barbara De Berardis ◽  
Magda Marchetti ◽  
Anna Risuglia ◽  
Federica Ietto ◽  
Carla Fanizza ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Human Health ◽  
Large Scale ◽  
Current Knowledge ◽  
Engineered Nanoparticles ◽  
In Vivo Studies ◽  
Field Exposure ◽  
The Impact

AbstractIn recent years, the introduction of innovative low-cost and large-scale processes for the synthesis of engineered nanoparticles with at least one dimension less than 100 nm has led to countless useful and extensive applications. In this context, gold nanoparticles stimulated a growing interest, due to their peculiar characteristics such as ease of synthesis, chemical stability and optical properties. This stirred the development of numerous applications especially in the biomedical field. Exposure of manufacturers and consumers to industrial products containing nanoparticles poses a potential risk to human health and the environment. Despite this, the precise mechanisms of nanomaterial toxicity have not yet been fully elucidated. It is well known that the three main routes of exposure to nanomaterials are by inhalation, ingestion and through the skin, with inhalation being the most common route of exposure to NPs in the workplace. To provide a complete picture of the impact of inhaled gold nanoparticles on human health, in this article, we review the current knowledge about the physico-chemical characteristics of this nanomaterial, in the size range of 1–100 nm, and its toxicity for pulmonary structures both in vitro and in vivo. Studies comparing the toxic effect of NPs larger than 100 nm (up to 250 nm) are also discussed.

scholarly journals Impact of Mucin on Drug Diffusion: Development of a Straightforward In Vitro Method for the Determination of Drug Diffusivity in the Presence of Mucin

Pharmaceutics ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 168 ◽  
Author(s):  
Margherita Falavigna ◽  
Paul Stein ◽  
Gøril Flaten ◽  
Massimiliano di Cagno
Keyword(s):  
Drug Interaction ◽  
Drug Absorption ◽  
Cost Effective ◽  
Physicochemical Characteristics ◽  
In Vivo Studies ◽  
Phospholipid Vesicle ◽  
Mucus Layer ◽  
The Impact

Mucosal drug delivery accounts for various administration routes (i.e., oral, vaginal, ocular, pulmonary, etc.) and offers a vast surface for the permeation of drugs. However, the mucus layer which shields and lubricates all mucosal tissues can compromise drugs from reaching the epithelial site, thus affecting their absorption and therapeutic effect. Therefore, the effect of the mucus layer on drug absorption has to be evaluated early in the drug-development phase, prior to in vivo studies. For this reason, we developed a simple, cost-effective and reproducible method employing UV-visible localized spectroscopy for the assessment of the interaction between mucin and drugs with different physicochemical characteristics. The mucin–drug interaction was investigated by measuring the drug relative diffusivity (Drel) in the presence of mucin, and the method was validated by fitting experimental and mathematical data. In vitro permeability studies were also performed using the mucus-covered artificial permeation barrier (mucus–PVPA, Phospholipid Vesicle-based Permeation Assay) for comparison. The obtained results showed that the diffusion of drugs was hampered by the presence of mucin, especially at higher concentrations. This novel method proved to be suitable for the investigation on the extent of mucin–drug interaction and can be successfully used to assess the impact that the mucus layer has on drug absorption.

scholarly journals Lysine Acetylation Regulates Alanyl-tRNA Synthetase Activity in Escherichia coli

Genes ◽  
2018 ◽  
Vol 9 (10) ◽  
pp. 473 ◽  
Author(s):  
Takuya Umehara ◽  
Saori Kosono ◽  
Dieter Söll ◽  
Koji Tamura
Keyword(s):  
Escherichia Coli ◽  
Trna Synthetase ◽  
Synthetase Activity ◽  
Lysine Acetylation ◽  
Trna Synthetases ◽  
E Coli ◽  
Domains Of Life ◽  
The Impact

Protein lysine acetylation is a widely conserved posttranslational modification in all three domains of life. Lysine acetylation frequently occurs in aminoacyl-tRNA synthetases (aaRSs) from many organisms. In this study, we determined the impact of the naturally occurring acetylation at lysine-73 (K73) in Escherichia coli class II alanyl-tRNA synthetase (AlaRS) on its alanylation activity. We prepared an AlaRS K73Ac variant in which Nε-acetyl-l-lysine was incorporated at position 73 using an expanded genetic code system in E. coli. The AlaRS K73Ac variant showed low activity compared to the AlaRS wild type (WT). Nicotinamide treatment or CobB-deletion in an E. coli led to elevated acetylation levels of AlaRS K73Ac and strongly reduced alanylation activities. We assumed that alanylation by AlaRS is affected by K73 acetylation, and the modification is sensitive to CobB deacetylase in vivo. We also showed that E. coli expresses two CobB isoforms (CobB-L and CobB-S) in vivo. CobB-S displayed the deacetylase activity of the AlaRS K73Ac variant in vitro. Our results imply a potential regulatory role for lysine acetylation in controlling the activity of aaRSs and protein synthesis.

scholarly journals Use of isotopically labeled substrates reveals kinetic differences between human and bacterial serine palmitoyltransferase

2019 ◽  
Vol 60 (5) ◽  
pp. 953-962 ◽  
Author(s):  
Peter J. Harrison ◽  
Kenneth Gable ◽  
Niranjanakumari Somashekarappa ◽  
Van Kelly ◽  
David J. Clarke ◽  
...  
Keyword(s):  
In Vivo Studies ◽  
Serine Palmitoyltransferase ◽  
Biochemical Pathways ◽  
Catalytic Mechanisms ◽  
Catalyzed Reactions ◽  
Enzyme Catalyzed Reactions ◽  
The Impact ◽  
Sphingolipid Biosynthesis

Isotope labels are frequently used tools to track metabolites through complex biochemical pathways and to discern the mechanisms of enzyme-catalyzed reactions. Isotopically labeled l-serine is often used to monitor the activity of the first enzyme in sphingolipid biosynthesis, serine palmitoyltransferase (SPT), as well as labeling downstream cellular metabolites. Intrigued by the effect that isotope labels may be having on SPT catalysis, we characterized the impact of different l-serine isotopologues on the catalytic activity of recombinant SPT isozymes from humans and the bacterium Sphingomonas paucimobilis. Our data show that S. paucimobilis SPT activity displays a clear isotope effect with [2,3,3-D]l-serine, whereas the human SPT isoform does not. This suggests that although both human and S. paucimobilis SPT catalyze the same chemical reaction, there may well be underlying subtle differences in their catalytic mechanisms. Our results suggest that it is the activating small subunits of human SPT that play a key role in these mechanistic variations. This study also highlights that it is important to consider the type and location of isotope labels on a substrate when they are to be used in in vitro and in vivo studies.

scholarly journals In Vitro and In Vivo Studies of Biodegradability and Biocompatibility of Poly(εCL)-b-Poly(EtOEP)-Based Films

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3039
Author(s):  
Ilya Nifant’ev ◽  
Andrey Shlyakhtin ◽  
Pavel Komarov ◽  
Alexander Tavtorkin ◽  
Evgeniya Kananykhina ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
Block Copolymers ◽  
Polymer Films ◽  
Hydrolytic Stability ◽  
Polymer Materials ◽  
In Vivo Studies ◽  
Cytotoxicity Test ◽  
The Impact

The control of surface bioadhesive properties of the subcutaneous implants is essential for the development of biosensors and controlled drug release devices. Poly(alkyl ethylene phosphate)-based (co)polymers are structurally versatile, biocompatible and biodegradable, and may be regarded as an alternative to poly(ethylene glycol) (PEG) copolymers in the creation of antiadhesive materials. The present work reports the synthesis of block copolymers of ε-caprolactone (εCL) and 2-ethoxy-1,3,2-dioxaphospholane-2-oxide (ethyl ethylene phosphate, EtOEP) with different content of EtOEP fragments, preparation of polymer films, and the results of the study of the impact of EtOEP/εCL ratio on the hydrophilicity (contact angle of wetting), hydrolytic stability, cytotoxicity, protein and cell adhesion, and cell proliferation using umbilical cord multipotent stem cells. It was found that the increase of EtOEP/εCL ratio results in increase of hydrophilicity of the polymer films with lowering of the protein and cell adhesion. MTT cytotoxicity test showed no significant deviations in toxicity of poly(εCL) and poly(εCL)-b-poly(EtOEP)-based films. The influence of the length of poly(EtOEP)chain in block-copolymers on fibrotic reactions was analyzed using subcutaneous implantation experiments (Wistar line rats), the increase of the width of the fibrous capsule correlated with higher EtOEP/εCL ratio. However, the copolymer-based film with highest content of polyphosphate had been subjected to faster degradation with a formation of developed contact surface of poly(εCL). The rate of the degradation of polyphosphate in vivo was significantly higher than the rate of the degradation of polyphosphate in vitro, which only confirms an objective value of in vivo experiments in the development of polymer materials for biomedical applications.

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