Influence of several drugs on the in vivo and in vitro activity of mammalian hepatic azo-reductase

1968 ◽  
Vol 46 (4) ◽  
pp. 367-371 ◽  
Author(s):  
John V. Burba
Keyword(s):  
Guinea Pigs ◽  
Marked Decrease ◽  
Reductase Activity ◽  
Sulfanilic Acid ◽  
In Vitro Activity ◽  
Appreciable Increase ◽  
Azo Reductase

The ability of a variety of drugs to influence liver azo-reductase activity of rabbits, rats, and guinea pigs in vitro was determined. Only nitrofurantoin showed a marked stimulatory activity in the three species. There was no appreciable inhibitory activity with any of the drugs tested. Determination of azo-reductase activity in vivo after pretreatment of the animals with phenobarbital and nitrofurantoin showed that there was an appreciable increase only in the azo-reductase activity of rats with phenobarbital, and only rabbits showed a marked decrease in azo-reductase activity with nitrofurantoin. Under the same conditions there was an appreciable increase in the excretion of N-acetylated sulfanilic acid by phenobarbital-pretreated rats and guinea pigs, while with nitrofurantoin rabbits showed an increase and rats a large decrease in the excretion of N-acetylated sulfanilic acid.

scholarly journals Comparison of Two Methods and Three End Points in Determination of In Vitro Activity of Micafungin against Aspergillus spp

2003 ◽  
Vol 47 (8) ◽  
pp. 2640-2643 ◽  
Author(s):  
Sevtap Arikan ◽  
Pınar Yurdakul ◽  
Gulsen Hascelik
Keyword(s):  
Vitro Activity ◽  
Disk Diffusion ◽  
In Vitro Activity ◽  
End Points ◽  
Minimum Effective Concentration ◽  
Disk Diffusion Assay ◽  
Diffusion Assay

ABSTRACT We investigated the in vitro activity of micafungin against clinical Aspergillus isolates (n = 37) (Aspergillusfumigatus [n = 21], Aspergillusflavus [n = 14], and Aspergillus niger [n = 2]) by using NCCLS M38A microdilution and an investigational disk diffusion assay. Microdilution assay results were evaluated by using the end points of a MIC-2 (measured in micrograms per milliliter) and minimum effective concentration (MEC, measured in micrograms per milliliter; the lowest concentration of micafungin that produces short and aberrant hyphal branchings microscopically). Disk diffusion results were interpreted by measuring the zone(s) of inhibition (ZOI, measured in millimeters). Micafungin proved to be similarly active against all Aspergillus species tested. At 24 h, MIC-2s and MECs were identical. At 48 h, however, MIC-2s increased unpredictably, leading to the loss of a consistent correlation between the two end points. MECs and ZOI remained consistent and correlated at both reading times, suggesting their use as relevant end points in susceptibility testing of micafungin against Aspergillus. All Aspergillus isolates yielded intrazonal growth on disk diffusion agar plates. The intrazonal colonies contained short, aberrant hyphal branchings microscopically. The in vivo significance of these findings remains to be further investigated.

Inhibition of 17β-hydroxysteroid-oxidoreductase activity in purified rat Leydig cells by single injection of human choriogonadotrophin

1984 ◽  
Vol 105 (4) ◽  
pp. 571-576 ◽  
Author(s):  
Nikolaus Kühn-Velten ◽  
Wolfgang Staib
Keyword(s):  
Leydig Cells ◽  
Time Course ◽  
Marked Decrease ◽  
Single Injection ◽  
Reductase Activity ◽  
Competitive Inhibitor ◽  
Oxidoreductase Activity ◽  
Rate Limiting

Abstract. A marked decrease of progesterone conversion to androgens in vitro by purified rat testis Leydig cells is observed from 1/2 to 3 days after treatment of the rats with 100 IU human choriogonadotrophin (hCG) in vivo. The maximal inhibition results 2 days after hCG injection and is denoted by a 72% reduction of androstenedione formation and a 78% reduction of testosterone formation from 2.5 μmol progesterone · l7#x2212;1. The testosterone/androstenedione ratio (about 0.4), however, is not changed after hCG treatment, indicating that the 17-ketosteroid-reductase activity is not rate-limiting under these conditions. Nevertheless, testosterone formation from 2.5 μmol androstenedione · l−1 is reduced by 67% and androstenedione formation from 2.5 μmol testosterone · l−1 is reduced by 79% 1 and 2 days after hCG treatment. The time-course of this hCG-induced decrease in both reductase and oxidase activities of the Leydig cell 17β-hydroxysteroid-oxidoreductase parallels the decrease of androgen formation from progesterone. Kinetic analyses reveal that the Vmax of the oxidase is reduced to a significantly (P < 0.05) greater extent than the Vmax of the reductase (79 and 62%, respectively), whereas the respective Km values remain unchanged. From these results it may be concluded that either a loss, or an inactivation of the enzyme protein, or the formation of non-competitive inhibitor occur during hCG action and that hCG may affect different enzyme activities involved in testicular androgen biosynthesis in a similar way.

A Molecular Approach to Immunoscintigraphy: A Study of the T-Antigen Conformation on the Surface of Tumors

1987 ◽  
Vol 26 (01) ◽  
pp. 1-6 ◽  
Author(s):  
S. Selvaraj ◽  
M. R. Suresh ◽  
G. McLean ◽  
D. Willans ◽  
C. Turner ◽  
...  
Keyword(s):  
Monoclonal Antibodies ◽  
Tumor Cell ◽  
T Antigen ◽  
Human Carcinomas ◽  
Animal Tumor ◽  
Synthetic Antigens

The role of glycoconjugates in tumor cell differentiation has been well documented. We have examined the expression of the two anomers of the Thomsen-Friedenreich antigen on the surface of human, canine and murine tumor cell membranes both in vitro and in vivo. This has been accomplished through the synthesis of the disaccharide terminal residues in both a and ß configuration. Both entities were used to generate murine monoclonal antibodies which recognized the carbohydrate determinants. The determination of fine specificities of these antibodies was effected by means of cellular uptake, immunohistopathology and immunoscintigraphy. Examination of pathological specimens of human and canine tumor tissue indicated that the expressed antigen was in the β configuration. More than 89% of all human carcinomas tested expressed the antigen in the above anomeric form. The combination of synthetic antigens and monoclonal antibodies raised specifically against them provide us with invaluable tools for the study of tumor marker expression in humans and their respective animal tumor models.

Storage of Human Blood Platelets

1974 ◽  
Vol 32 (02/03) ◽  
pp. 405-416 ◽  
Author(s):  
M. R Hardeman ◽  
Carina J L. Heynens
Keyword(s):  
Storage Temperature ◽  
Platelet Rich Plasma ◽  
Blood Platelets ◽  
Storage Period ◽  
Serotonin Uptake ◽  
Hypotonic Shock ◽  
Glycolytic Intermediates

SummaryStorage experiments were performed at 4°, 25° and 37° C with platelet-rich plasma under sterile conditions. In some experiments also the effect of storing platelets at 4° C in whole blood was investigated.Before, during and after three days of storage, the platelets were tested at 37° C for their serotonin uptake and response to hypotonic shock. In addition some glycolytic intermediates were determined.A fair correlation was noticed between the serotonin uptake and hypotonic shock experiments. Both parameters were best maintained at 25° C. Also platelet counting, performed after the storage period, indicated 25° C as the best storage temperature. Determination of glycolytic intermediates did not justify any conclusion regarding the optimal storage temperature. Of the various anticoagulants studied, ACD and heparin gave the best results as to the serotonin uptake and hypotonic shock response, either with fresh or stored platelets. The use of EDTA resulted in the lowest activity, especially after storage.The results of these storage experiments in vitro, correspond well with those in vivo reported in the literature.

Inhibition of Human and Animal Platelet Adhesiveness to Glass Bead Columns by Adenosine, Dipyridamole, Chlorpromazine and Acetylsalicylic Acid

1976 ◽  
Vol 36 (02) ◽  
pp. 401-410 ◽  
Author(s):  
Buichi Fujttani ◽  
Toshimichi Tsuboi ◽  
Kazuko Takeno ◽  
Kouichi Yoshida ◽  
Masanao Shimizu
Keyword(s):  
Guinea Pig ◽  
Acetylsalicylic Acid ◽  
Guinea Pigs ◽  
Glass Bead ◽  
Animal Species ◽  
Inhibitory Effect ◽  
Rabbit Platelet ◽  
Platelet Adhesiveness

SummaryThe differences among human, rabbit and guinea-pig platelet adhesiveness as for inhibitions by adenosine, dipyridamole, chlorpromazine and acetylsalicylic acid are described, and the influence of measurement conditions on platelet adhesiveness is also reported. Platelet adhesiveness of human and animal species decreased with an increase of heparin concentrations and an increase of flow rate of blood passing through a glass bead column. Human and rabbit platelet adhesiveness was inhibited in vitro by adenosine, dipyridamole and chlorpromazine, but not by acetylsalicylic acid. On the other hand, guinea-pig platelet adhesiveness was inhibited by the four drugs including acetylsalicylic acid. In in vivo study, adenosine, dipyridamole and chlorpromazine inhibited platelet adhesiveness in rabbits and guinea-pigs. Acetylsalicylic acid showed the inhibitory effect in guinea-pigs, but not in rabbits.

Carbon dots derived from Fusobacterium nucleatum for intracellular determination of Fe3+ and bioimaging both in vitro and in vivo

2021 ◽  
Author(s):  
Lijuan Liu ◽  
Shengting Zhang ◽  
Xiaodan Zheng ◽  
Hongmei Li ◽  
Qi Chen ◽  
...  
Keyword(s):  
Carbon Dots ◽  
Fusobacterium Nucleatum ◽  
Living Cells ◽  
First Time ◽  
Fluorescent Carbon Dots ◽  
Fluorescent Carbon

Fusobacterium nucleatum has been employed for the first time to synthesize fluorescent carbon dots which could be applied for the determination of Fe3+ ions in living cells and bioimaging in vitro and in vivo with excellent biocompatibility.

scholarly journals Intracellular localisation of Mycobacterium tuberculosis affects efficacy of the antibiotic pyrazinamide

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Pierre Santucci ◽  
Daniel J. Greenwood ◽  
Antony Fearns ◽  
Kai Chen ◽  
Haibo Jiang ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Host Cell ◽  
Combination Chemotherapy ◽  
In Vitro Activity ◽  
In Vivo Efficacy ◽  
Human Macrophages ◽  
Ion Microscopy ◽  
Intracellular Localisation

AbstractTo be effective, chemotherapy against tuberculosis (TB) must kill the intracellular population of the pathogen, Mycobacterium tuberculosis. However, how host cell microenvironments affect antibiotic accumulation and efficacy remains unclear. Here, we use correlative light, electron, and ion microscopy to investigate how various microenvironments within human macrophages affect the activity of pyrazinamide (PZA), a key antibiotic against TB. We show that PZA accumulates heterogeneously among individual bacteria in multiple host cell environments. Crucially, PZA accumulation and efficacy is maximal within acidified phagosomes. Bedaquiline, another antibiotic commonly used in combined TB therapy, enhances PZA accumulation via a host cell-mediated mechanism. Thus, intracellular localisation and specific microenvironments affect PZA accumulation and efficacy. Our results may explain the potent in vivo efficacy of PZA, compared to its modest in vitro activity, and its critical contribution to TB combination chemotherapy.

Factors affecting in vitro and in vivo antioxidant effects. Experimental conditions and nature of oxidants determine antioxidant efficacy

2021 ◽  
pp. 1-9
Author(s):  
Etsuo Niki
Keyword(s):  
Biological Molecules ◽  
Experimental Conditions ◽  
Factors Affecting ◽  
Beneficial Effects ◽  
Multiple Oxidants ◽  
Antioxidant Effects

Reactive oxygen and nitrogen species have been implicated in the onset and progression of various diseases and the role of antioxidants in the maintenance of health and prevention of diseases has received much attention. The action and effect of antioxidants have been studied extensively under different reaction conditions in multiple media. The antioxidant effects are determined by many factors. This review aims to discuss several important issues that should be considered for determination of experimental conditions and interpretation of experimental results in order to understand the beneficial effects and limit of antioxidants against detrimental oxidation of biological molecules. Emphasis was laid on cell culture experiments and effects of diversity of multiple oxidants on antioxidant efficacy.

Antimicrobial and antibiofilm activities of meropenem loaded-mesoporous silica nanoparticles against carbapenem-resistant Pseudomonas aeruginosa

2021 ◽  
pp. 088532822110038
Author(s):  
Mohammad Yousef Memar ◽  
Mina Yekani ◽  
Hadi Ghanbari ◽  
Edris Nabizadeh ◽  
Sepideh Zununi Vahed ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Mesoporous Silica ◽  
Silica Nanoparticles ◽  
Mesoporous Silica Nanoparticles ◽  
Carbapenem Resistant ◽  
Toxicity In Vitro ◽  
Different Levels

The aims of the present study were the determination of antimicrobial and antibiofilm effects of meropenem-loaded mesoporous silica nanoparticles (MSNs) on carbapenem resistant Pseudomonas aeruginosa ( P. aeruginosa) and cytotoxicity properties in vitro. The meropenem-loaded MSNs had shown antibacterial and biofilm inhibitory activities on all isolates at different levels lower than MICs and BICs of meropenem. The viability of HC-04 cells treated with serial concentrations as MICs and BICs of meropenem-loaded MSNs was 92–100%. According to the obtained results, meropenem-loaded MSNs display the significant antibacterial and antibiofilm effects against carbapenem resistant and biofilm forming P. aeruginosa and low cell toxicity in vitro. Then, the prepared system can be an appropriate option for the delivery of carbapenem for further evaluation in vivo assays.

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