scholarly journals FURTHER STUDIES ON PREPARATION AND PROPERTIES OF PHAGOCYTIN

1960 ◽  
Vol 111 (3) ◽  
pp. 323-337 ◽  
Author(s):  
James G. Hirsch
Keyword(s):  
Citric Acid ◽  
Ionic Strength ◽  
Lethal Effect ◽  
Coliform Bacteria ◽  
Polymorphonuclear Leucocytes ◽  
In Vitro Test ◽  
Bactericidal Action ◽  
Gram Positive ◽  
Trichloracetic Acid

Phagocytin and histone differ significantly in the following regards: (a) the bactericidal action of histone is rapidly lost on peptic digestion, while that of phagocytin is but little affected; (b) the lethal effect of phagocytin on coliform bacteria is much more resistant than that of histone to antagonism by spermine or by increasing ionic strength of the medium; (c) phagocytin can be extracted from disrupted granulocytes with dilute citric acid whereas effective extraction of histone requires stronger mineral acid or strong salt solution; (d) phagocytin is limited in distribution to polymorphonuclear leucocytes while histone is demonstrable in many tissues. A new technique has been devised which permits extraction of phagocytin essentially free of lysozyme and histones. Phagocytin thus prepared kills certain Gram-positive bacteria as well as Gram-negative bacilli under appropriate in vitro test conditions. Among susceptible Gram-positive microbes are Group A streptococci and staphylococci. Phagocytin is demonstrable in citric acid extracts of granulocytes obtained from rabbit, man, horse, and guinea pig, the only species thus far investigated. Circulating blood leucocytes as well as exudate cells contain this bactericidal substance. The lethal effects of phagocytin on bacteria may be influenced, depending on the particular microorganism, by either pH or ionic strength of the medium. The bactericidal action of phagocytin is only slightly reduced following digestion with trypsin, chymotrypsin or papain. The active ingredient is, however, non-dialyzable and apparently precipitated by trichloracetic acid. Data available at present are insufficient to define the chemical nature of phagocytin.

scholarly journals THE ANTIBACTERIAL ACTIVITY OF HEMOGLOBIN

1958 ◽  
Vol 107 (2) ◽  
pp. 167-183 ◽  
Author(s):  
Derek Hobson ◽  
James G. Hirsch
Keyword(s):  
Bactericidal Activity ◽  
Lethal Effect ◽  
Bactericidal Effect ◽  
Mineral Acid ◽  
Ionic Concentration ◽  
Coliform Bacteria ◽  
Bactericidal Action ◽  
Lethal Action ◽  
Serum Fractions

Low concentrations of hemoglobin (0.1 µg./ml. or less) exert a lethal action on some Gram-negative bacteria under certain conditions in vitro. Hemoglobins from various mammals and the distinct genetic types of human hemoglobin all manifest similar bactericidal activity. The bactericidal effect is a function of the globin moiety of the molecule; native and acid or acid-alcohol denatured globins have the same degree of activity. Hemoglobins kill enterobacteriaceae only under precisely controlled conditions. The test medium must be low in ionic concentration and acid in reaction. Various strains of Escherichia and Salmonella are susceptible to the lethal effect of hemoglobin, while the few strains of Shigella, Klebsiella, and Proteus examined were resistant. Certain acid polysaccharides and basic amines or proteins block the bactericidal effect when incorporated in the test in low concentration. Present evidence also suggests that exposure of the microorganisms to certain cations such as magnesium renders them resistant to the lethal action of globin. Hemoglobin loses its bactericidal power when complexed with haptoglobin, and serum fractions rich in free haptoglobin protect otherwise susceptible bacteria from killing by hemoglobin. The reaction appears to be a bactericidal rather than a bacteriostatic one. At 38°C. maximal killing requires approximately 30 minutes; at temperatures of 28°C. or 0°C. the bactericidal action does not take place. The minimal concentration of hemoglobin required to kill 50 per cent of the microorganisms in the test is unrelated to the size of the bacterial inoculum. Under conditions suitable for bactericidal action, hemoglobin is adsorbed onto heat-killed susceptible strains of coliform bacteria; material possessing bactericidal activity can be eluted with dilute mineral acid.

Distinctive properties of glutamine synthetase from the cyanobacterium Anacystis nidulans

1979 ◽  
Vol 57 (6) ◽  
pp. 843-851 ◽  
Author(s):  
Diane Emond ◽  
Normand Rondeau ◽  
R. J. Cedergren
Keyword(s):  
Ionic Strength ◽  
Glutamine Synthetase ◽  
Ammonium Sulfate ◽  
Anacystis Nidulans ◽  
Partial Purification ◽  
In Vitro Test ◽  
Membrane Complex ◽  
Vitro Test ◽  
Glutamyl Transferase

The intracellular levels of glutamine synthetase (GS) in Anacystis nidulans grown under different conditions were determined using a whole-cell assay. Nitrate-grown cells have 64% more GS than cells grown in ammonium sulfate. Nitrogen starvation does not affect GS levels appreciably. Incubation of nitrate-grown cells with ammonium sulfate does not change the ratio of γ-glutamyl transferase activities stimulated by Mg2+ and Mn2+ ions. An in vitro test of adenylylation indicates that algae do not have an endogenous adenylyl transferase (ATase) and that algal GS is not adenylylatable by the Klebsiella aerogenes ATase. Some characteristics of the GS–membrane complex were determined by centrifugation of the complex under varying conditions of pH and ionic strength. In this way, it was shown that acid pH (4.5) stabilizes the complex and high ionic strength tends to solubilize the enzyme. A simple partial purification of GS (89-fold) was developed based on the sedimentation properties of GS.

Haemostatic Platelet Plug Formation in the Isolated Rabbit Mesenteric Preparation - An Analysis of Red Blood Cell Participation

1980 ◽  
Vol 44 (01) ◽  
pp. 006-008 ◽  
Author(s):  
D Bergqvist ◽  
K-E Arfors
Keyword(s):  
Whole Blood ◽  
Platelet Rich Plasma ◽  
Adenosine Diphosphate ◽  
In Vitro Test ◽  
Pharmacological Agents ◽  
Vitro Test ◽  
Releasing Effect ◽  
Plug Formation

SummaryIn a model using an isolated rabbit mesenteric preparation microvessels were transected and the time until haemostatic plugs formed was registered. Perfusion of platelet rich plasma gave no haemostasis whereas whole blood did. Addition of chlorpromazine or adenosine to the whole blood significantly prolonged the time for haemostasis, and addition of ADP to the platelet rich plasma significantly shortened it. It is concluded that red cells are necessary for a normal haemostasis in this model, probably by a combination of a haemodynamic and ADP releasing effect.The fundamental role of platelets in haemostatic plug formation is unquestionable but there are still problems concerning the stimulus for this process to start. Three platelet aggregating substances have been discussed – thrombin, adenosine diphosphate (ADP) and collagen. Evidence speaking in favour of thrombin is, however, very minimal, and the discussion has to be focused on collagen and ADP. In an in vitro system using polyethylene tubings we have shown that "haemostasis" can be obtained without the presence of collagen but against these results can be argued that it is only another in vitro test for platelet aggregation (1).To be able to induce haemostasis in this model, however, the presence of red blood cells is necessary. To further study this problem we have developed a model where haemostatic plug formation can be studied in the isolated rabbit mesentery and we have briefly reported on this (2).Thus, it is possible to perfuse the vessels with whole blood as well as with platelet rich plasma (PRP) and different pharmacological agents of importance.

Antimicrobial Activity For Crud EWatery Extract Of Seeds Of Citrus Aurantifolia (Lime Fruit) Against Gram Positive And Negative Bacteria In Vitro

2016 ◽  
pp. 404
Author(s):  
بهاء عبدالله لفتة الربيعى ◽  
هند حسين عبيد ◽  
تحرير هادى صالح
Keyword(s):  
Antimicrobial Activity ◽  
Gram Positive ◽  
Citrus Aurantifolia

scholarly journals Development and In Vitro-In Vivo Evaluation of a Novel Sustained-Release Loxoprofen Pellet with Double Coating Layer

Pharmaceutics ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 260 ◽  
Author(s):  
Dongwei Wan ◽  
Min Zhao ◽  
Jingjing Zhang ◽  
Libiao Luan
Keyword(s):  
Citric Acid ◽  
Drug Release ◽  
Sustained Release ◽  
Release Rate ◽  
Diffusion Rate ◽  
Immediate Release ◽  
Pharmacokinetic Studies ◽  
Release Tablet

This study aimed to develop a novel sustained release pellet of loxoprofen sodium (LXP) by coating a dissolution-rate controlling sub-layer containing hydroxypropyl methyl cellulose (HPMC) and citric acid, and a second diffusion-rate controlling layer containing aqueous dispersion of ethyl cellulose (ADEC) on the surface of a LXP conventional pellet, and to compare its performance in vivo with an immediate release tablet (Loxinon®). A three-level, three-factor Box-Behnken design and the response surface model (RSM) were used to investigate and optimize the effects of the citric acid content in the sub-layer, the sub-layer coating level, and the outer ADEC coating level on the in vitro release profiles of LXP sustained release pellets. The pharmacokinetic studies of the optimal sustained release pellets were performed in fasted beagle dogs using an immediate release tablet as a reference. The results illustrated that both the citric acid (CA) and ADEC as the dissolution- and diffusion-rate controlling materials significantly decreased the drug release rate. The optimal formulation showed a pH-independent drug release in media at pH above 4.5 and a slightly slow release in acid medium. The pharmacokinetic studies revealed that a more stable and prolonged plasma drug concentration profile of the optimal pellets was achieved, with a relative bioavaibility of 87.16% compared with the conventional tablets. This article provided a novel concept of two-step control of the release rate of LXP, which showed a sustained release both in vitro and in vivo.

scholarly journals In Vitro Newly Isolated Environmental Phage Activity against Biofilms Preformed by Pseudomonas aeruginosa from Patients with Cystic Fibrosis

2021 ◽  
Vol 9 (3) ◽  
pp. 478
Author(s):  
Ersilia Vita Fiscarelli ◽  
Martina Rossitto ◽  
Paola Rosati ◽  
Nour Essa ◽  
Valentina Crocetta ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Pseudomonas Aeruginosa ◽  
Multidrug Resistant ◽  
In Vitro Test ◽  
Chronic Infections ◽  
Hospital Environments ◽  
Vitro Test ◽  
General Reliability ◽  
Phage Activity

As disease worsens in patients with cystic fibrosis (CF), Pseudomonas aeruginosa (PA) colonizes the lungs, causing pulmonary failure and mortality. Progressively, PA forms typical biofilms, and antibiotic treatments determine multidrug-resistant (MDR) PA strains. To advance new therapies against MDR PA, research has reappraised bacteriophages (phages), viruses naturally infecting bacteria. Because few in vitro studies have tested phages on CF PA biofilms, general reliability remains unclear. This study aimed to test in vitro newly isolated environmental phage activity against PA isolates from patients with CF at Bambino Gesù Children’s Hospital (OBG), Rome, Italy. After testing in vitro phage activities, we combined phages with amikacin, meropenem, and tobramycin against CF PA pre-formed biofilms. We also investigated new emerging morphotypes and bacterial regrowth. We obtained 22 newly isolated phages from various environments, including OBG. In about 94% of 32 CF PA isolates tested, these phages showed in vitro PA lysis. Despite poor efficacy against chronic CF PA, five selected-lytic-phages (Φ4_ZP1, Φ9_ZP2, Φ14_OBG, Φ17_OBG, and Φ19_OBG) showed wide host activity. The Φ4_ZP1-meropenem and Φ14_OBG-tobramycin combinations significantly reduced CF PA biofilms (p < 0.001). To advance potential combined phage-antibiotic therapy, we envisage further in vitro test combinations with newly isolated phages, including those from hospital environments, against CF PA biofilms from early and chronic infections.

scholarly journals Effect of Citric Acid on Color Changes of Calcium Silicate-Based Cements an In Vitro Study

2021 ◽  
Vol 11 (5) ◽  
pp. 2339
Author(s):  
Joanna Metlerska ◽  
Till Dammaschke ◽  
Mariusz Lipski ◽  
Irini Fagogeni ◽  
Anna Machoy-Mokrzyńska ◽  
...  
Keyword(s):  
Citric Acid ◽  
Calcium Silicate ◽  
In Vitro Study ◽  
Vitro Study ◽  
Color Measurement ◽  
Color Changes ◽  
Naked Eye ◽  
Root Canal Irrigants ◽  
The Difference

The aim of the present in vitro study was to investigate the effects of 10% and 40% citric acid (CA) on the color of calcium silicate–based cements (CSCs) in comparison to the effects of common root canal irrigants. Samples of six CSCs (n = 6)—ProRoot MTA (Dentsply, Tulsa, OK, USA), Biodentine (Septodont, Saint-Maur-des-Fossés, France), MTA Plus (Avalon Biomed Inc, by Prevest Denpro Limited, Jammu, India), MTA Repair HP (Angelus, Londrina, PR, Brazil), Ortho MTA (BioMTA, Seoul, Korea), and Retro MTA (BioMTA, Seoul, Korea)—were immersed in 10% and 40% CA as well as 15% EDTA, 2% NaOCl, 2% CHX, and 0.9% NaCl for 15 min, 1 h, and 24 h. ΔE values, representing the difference between the final and baseline values of the color components, were then determined using a VITA Easyshade Compact 5.0 spectrophotometer. Naked-eye evaluation of the changes in color and structures of the materials was performed using our own scale. Upon immersion of the materials in both 10% and 40% CA, there were statistically significant differences between spectrophotometric color measurement results for all CSCs (P < 0.05). However, CA does not cause dark discoloration, observable with the naked eye, of any of the materials, such as NaOCl and CHX. Significant statistical differences were also found between all CSCs in terms of submersion duration (P < 0.05). CA, which could be an alternative to EDTA use, caused greater CSCs discoloration and changed some of their structures. Unless required by the therapeutic procedure, clinicians should pay attention to the fact that the irrigant may affect the CSCs discoloration and minimize the contact time of irrigant with CSCs.

The Use of Biomarkers as Alternatives to Current Animal Tests on Food Chemicals

1998 ◽  
Vol 26 (4) ◽  
pp. 421-480
Author(s):  
Krys Bottrill
Keyword(s):  
Animal Studies ◽  
Developmental Toxicity ◽  
Reproductive Toxicity ◽  
In Vitro Test ◽  
Animal Testing ◽  
Dietary Biomarkers ◽  
Recent Developments ◽  
Mechanistic Basis ◽  
The Three Rs

Recent developments in biomarkers relating to the interrelationship of diet, disease and health were surveyed. Most emphasis was placed on biomarkers of deleterious effects, since these are of greatest relevance to the subject of this review. The area of greatest activity was found to be that relating to biomarkers of mutagenic, genotoxic and carcinogenic effects. This is also one of the major areas of concern in considerations of the beneficial and deleterious effects of dietary components, and also the area in which regulatory testing requires studies of the longest duration. A degree of progress has also been made in the identification and development of biomarkers relating to certain classes of target organ toxicity. Biomarkers for other types of toxicity, such as immunotoxicity, neurotoxicity, reproductive toxicity and developmental toxicity, are less developed, and further investigation in these areas is required before a comprehensive biomarker strategy can be established. A criticism that recurs constantly in the biomarker literature is the lack of standardisation in the methods used, and the lack of reference standards for the purposes of validation and quality control. It is encouraging to note the growing acknowledgement of the need for validation of biomarkers and biomarker assays. Some validation studies have already been initiated. This review puts forward proposals for criteria to be used in biomarker validation. More discussion on this subject is required. It is concluded that the use of biomarkers can, in some cases, facilitate the implementation of the Three Rs with respect to the testing of food chemicals and studies on the effects of diet on health. The greatest potential is seen to be in the refinement of animal testing, in which biomarkers could serve as early and sensitive endpoints, in order to reduce the duration of the studies and also reduce the number of animals required. Biomarkers could also contribute to establishing a mechanistic basis for in vitro test systems and to facilitating their validation and acceptance. Finally, the increased information that could result from the incorporation of biomarker determinations into population studies could reduce the need for supplementary animal studies. This review makes a number of recommendations concerning the prioritisation of future activities on dietary biomarkers in relation to the Three Rs. It is emphasised, however, that further discussions will be required among toxicologists, epidemiologists and others researching the relationship between diet and health.

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