scholarly journals Paroxysmal Nocturnal Hemoglobinuria

Blood ◽  
1953 ◽  
Vol 8 (5) ◽  
pp. 444-458 ◽  
Author(s):  
WILLIAM H. CROSBY
Keyword(s):  
Hemolytic Activity ◽  
Soluble Fraction ◽  
Insoluble Fraction ◽  
Water Soluble ◽  
Red Cells ◽  
Distilled Water ◽  
Heat Stable ◽  
Heat Labile

Abstract This report demonstrates the role and to some extent the interrelations of various factors that are active in the PNH hemolytic system. 1. Activity of four plasma factors, probably protein in nature, has been demonstrated. Two of these factors are hemolytic against PNH red cells, but not against normal red cells. The other two inhibit PNH hemolysis. (a). The heat labile hemolytic factor is water soluble and is therefore present in the soluble fraction of serum that has been dialyzed against distilled water. It is almost completely destroyed by heating at 53 C. for 10 minutes. It is slowly inactivated by incubation at 37 C. with 100 units per ml. of thrombin. It is rapidly destroyed by concentrations of thrombin in excess of 200 units per ml. It is inactive unless the heat stable hemolytic factor is also present. (b). The heat stable hemolytic factor is insoluble in water and is therefore precipitated from serum by dialysis against distilled water. It is quite resistant to 100 units per ml. of thrombin and to incubation at 53 C. It is inactive unless the heat labile hemolytic factor is also present. (c). The heat labile inhibitor is insoluble in water and is therefore found in the insoluble fraction of serum dialyzed against distilled water. It is inactivated by heating at 53 C. for 10 minutes but not by incubation with 100 units per ml. of thrombin. (d). The heat stable inhibitor is found in the water-soluble fraction of dialyzed serum. It withstands dialysis poorly, but it is not affected by 30 minutes incubation at 53 C. Incubation at 37 C. with 100 units per ml. of thrombin for 10 minutes destroys its inhibitory activity. Apparently the inhibitors are not interdependent. 2. Calcium in small amounts is probably essential to the PNH hemolytic system. The concentration of calcium that is optimum for hemolysis lies in the neighborhood of 2.5 mM. The optimum is a little less than the amount normally present in the plasma. Calcium in excess inhibits hemolysis in vitro, and no hemolysis occurs when the concentration exceeds 25 mM. per liter. 3. Magnesium is also essential to the PNH hemolytic system. As magnesium is added to the system in vitro hemolytic activity increases until the concentration exceeds 10 mM. per liter. Amounts greater than that have some dampening effect. Magnesium appears to antagonize the heat stable inhibitor of the PNH hemolytic system. 4. Thrombin is involved in this system insofar as the heat stable inhibitor and the heat labile hemolytic factor may be destroyed by thrombic activity. The inhibitor is rapidly destroyed, the hemolytic factor slowly. Therefore, the sum of the reaction to small amounts of thrombin in the PNH hemolytic system is to increase hemolytic activity. 5. Dilute heparin and protamine increase the activity of the PNH hemolytic system in vitro, probably by blocking the two inhibitors. Heparin appears to work against the heat stable inhibitor, protamine against the heat labile inhibitor. 6. The intensity of PNH hemolytic activity whether in vitro or in vivo is probably related to a balance that exists between the inhibitors and the hemolytic factors. Hemolytic crises may occur when the hemolytic factors are increased or when their antagonists are depressed.

THE PRODUCTION BY BACILLUS THURINGIENSIS BERLINER OF A HEAT-STABLE SUBSTANCE TOXIC FOR INSECTS

1959 ◽  
Vol 5 (2) ◽  
pp. 161-168 ◽  
Author(s):  
Ellicott McConnell ◽  
A. Glenn Richards
Keyword(s):  
Bacillus Thuringiensis ◽  
Inclusion Bodies ◽  
Galleria Mellonella ◽  
Culture Media ◽  
Water Soluble ◽  
Broth Culture ◽  
Toxic Principle ◽  
Heat Stable

Bacillus thuringiensis Berliner produces in vitro a heat-stable, dialyzable substance which is toxic for insects when injected. The same or a similar substance is produced in vivo. The toxic principle is of unknown composition. It is heat-stable, water-soluble, dialyzable, and resistant to low temperatures. It is probably neither a protein nor a lipid. Clearly it is distinct from the heat-labile inclusion bodies and from lecithinase. Growth-curve studies showed that the heat-stable toxin appeared in liver broth cultures during the active growth phase, prior to the formation of spores or inclusion bodies. An attempt to produce the toxic principle from culture media in the absence of bacteria was unsuccessful from sterile inocula both from in vivo and in vitro sources. The LD50 for larvae of Galleria mellonella injected with autoclaved supernatant from a 10-day-old liver broth culture of B. thuringiensis was determined to be 0.00036 ml per larva or 0.002 ml per gram of larvae. Approximately the same level of toxicity was found for another caterpillar, a fly larva, and cockroaches. After larvae of Galleria or Pyrausla have been dead for more than 2 days from infection with B. thuringiensis the bacillus could no longer be recovered. A sublethal amount of the heat-stable toxin injected into old larvae of Galleria delayed emergence of the adults by 30 to 40%. The non-pathogenic Bacillus cereus was found to produce a similar-acting, heat-stable toxin under the same conditions that one is produced by B. thuringiensis.

scholarly journals Cyclic AMP Receptor Protein-Dependent Repression of Heat-Labile Enterotoxin

2008 ◽  
Vol 77 (2) ◽  
pp. 791-798 ◽  
Author(s):  
Maria D. Bodero ◽  
George P. Munson
Keyword(s):  
Cyclic Amp ◽  
Binding Sites ◽  
The Other ◽  
Receptor Protein ◽  
Heat Stable ◽  
Heat Labile ◽  
Dnase I Footprinting ◽  
Camp Receptor

ABSTRACT Enterotoxigenic Escherichia coli is a major cause of acute diarrheal illness worldwide and is responsible for high infant and child mortality rates in developing nations. Two types of enterotoxins, one heat labile and the other heat stable, are known to cause diarrhea. The expression of soluble heat-labile toxin is subject to catabolite (glucose) activation, and three binding sites for cAMP receptor protein (CRP or CAP) were identified upstream and within the toxin promoter by DNase I footprinting. One CRP operator is centered at −31.5, thus encompassing the promoter's −35 hexamer. Potassium permanganate footprinting revealed that the occupancy of this operator prevents RNA polymerase from forming an open complex in vitro. However, the operator centered at −31.5 is not sufficient for full repression in vivo because the deletion of the other two CRP binding sites partially relieved the CRP-dependent repression of the heat-labile toxin promoter. In contrast to heat-labile toxin, CRP positively regulates the expression of heat-stable toxin. Thus, the conditions for the optimal expression of one enterotoxin limit the expression of the other. Since glucose inhibits the activity of CRP by suppressing the pathogen's synthesis of cyclic AMP (cAMP), the concentration of glucose in the lumen of the small intestine may determine which enterotoxin is maximally expressed. In addition, our results suggest that the host may also modulate enterotoxin expression because cells intoxicated with heat-labile toxin overproduce and release cAMP.

Prediction of in vivo organic matter digestibility of beef cattle diets from degradation parameters estimated from in situ and in vitro incubations

2019 ◽  
Vol 157 (9-10) ◽  
pp. 711-720
Author(s):  
Pedro Del Bianco Benedeti ◽  
Sebastião de Campos Valadares Filho ◽  
Diego Zanetti ◽  
Fabyano Fonseca e Silva ◽  
Breno de Castro Silva ◽  
...  
Keyword(s):  
Organic Matter ◽  
Beef Cattle ◽  
Fixed Effects ◽  
Stepwise Regression ◽  
Meta Analysis ◽  
Insoluble Fraction ◽  
Water Soluble

AbstractThe objective of this meta-analysis study was to develop and validate equations estimated from in situ and in vitro methods to predict in vivo ruminal digestibility of organic matter (OM) of beef cattle diets. The database was composed of individual data of 23 diets from six experiments. Information collected from these studies was: in vivo digestibility and degradation parameters of OM calculated from in situ and in vitro incubations. The values of estimated times for the in situ and in vitro incubations to access in vivo digestibility of OM, and differences between degradation at 24, 48 and 72 h (in situ and in vitro) and in vivo digestibility were analysed in a model that included the fixed effects of forage neutral detergent fibre level. Thereafter, a multiple stepwise regression was carried out using OM digestibility as a dependent variable and degradation parameters (A = water-soluble fraction; B = potentially degradable water-insoluble fraction; and kd = degradation rate of fraction B) as independent variables. Equation validation was performed using data from a seventh experiment that have the same methods than previous studies. Stepwise regression results showed that the kd contributed significantly in most of the algorithms derived to predict in vivo digestibility. Validation analysis showed that equations developed from both in vitro and in situ incubations accurately estimated the in vivo digestibility of OM (P > 0.05). Our results suggest that equations developed to estimate OM digestibility showed both precision and accuracy; however, in situ method presented better results than in vitro.

scholarly journals THE PHENOMENON OF IN VITRO HEMOLYSIS PRODUCED BY THE RICKETTSIAE OF TYPHUS FEVER, WITH A NOTE ON THE MECHANISM OF RICKETTSIAL TOXICITY IN MICE

1948 ◽  
Vol 88 (1) ◽  
pp. 25-41 ◽  
Author(s):  
Delphine H. Clarke ◽  
John P. Fox
Keyword(s):  
Vascular Permeability ◽  
Hemolytic Activity ◽  
High Speed ◽  
Close Association ◽  
Inhibitory Effect ◽  
Yolk Sac ◽  
Red Cells ◽  
Cotton Rats

Suspensions of yolk sac infected with rickettsiae of murine or of epidemic typhus, and indeed suspensions of liver or peritoneal washings from cotton rats infected with these organisms, when the suspensions contain a sufficient concentration of living rickettsiae, possess the capacity to hemolyze, in vitro, red cells of rabbit or sheep origin. Under the same conditions such material did not cause the hemolysis of cells from mice, cotton rats, or guinea pigs. Yolk sac and tissue suspensions of R. orientalis (Karp, Raub, and Gilliam strains) failed to hemolyze rabbit cells. The hemolytic principle was destroyed by formol (0.5 per cent) and by heating to 56°C. for 1 hour. The close association of the "hemolysin" with the rickettsiae was indicated by their parallel movements on centrifugation and by the close parallel demonstrated between the effects produced on hemolytic activity and on such manifestations of the presence of living rickettsiae as toxicity for mice and lethality or total infectivity for cotton rats when infected yolk sac suspensions were exposed to elevated temperature or were concentrated by high-speed centrifugation. The mechanism of hemolysis remains ill defined. It progresses slowly, but never to completion (i.e. hemolysis of all the cells in the substrate) even when the number of such cells is small. This may be because hemolysis progresses best at temperatures (±35°C.) which are unfavorable to the hemolytic principle and because erythrocytes vary in their susceptibility to the injurious agent. The concentration of red cells also may be a determining factor, either by affecting the rate at which the reaction proceeds or by aiding in the preservation of hemolytic activity. Although it was impossible to separate the "hemolysin" from the rickettsiae, examination of smear preparations of hemolyzing mixtures showed no consistent contact relation between cells and rickettsiae. Adsorption experiments revealed that, while removal of the cells from the hemolytic system did not reduce the hemolyzing capacity of the system, the cells carried away a significant tendency to hemolyze. It is suggested that the rate at which injury is inflicted on the red cells is dependent on the concentration of "hemolysin" present and that the process may proceed in the relative absence of rickettsiae once sufficient damage has been inflicted. The toxicity of richly infected yolk sac suspensions for intravenously inoculated mice was found to be related, not to in vivo hemolysis, but apparently to a serious alteration in vascular permeability which caused a marked reduction in blood volume. This was evidenced by an increased concentration of red cells but not of plasma proteins. It is possible, but has not been demonstrated, that the factor responsible for altering vascular permeability of mice may be identical with that which causes lysis of rabbit and sheep cells. Two applications of the phenomenon of in vitro hemolysis are indicated. Following the technique described in the text for the optimum demonstration of hemolysis, the determination of the degree of hemolytic activity may serve as a rapid, roughly quantitative in vitro method for assessing the infectivity of a newly made rickettsial preparation. The phenomenon also is the basis for an additional, and potentially useful in vitro serologic technique which differs from other techniques in that it depends on a property of living rickettsiae. It has been shown that homologous antisera are capable of inhibiting hemolysis, and optimum conditions for demonstrating this inhibitory effect are described.

LACK OF EFFECT OF CORTICOSTEROIDS ON THE IN VIVO DISAPPEARANCE OF SULFHYDRYL-INHIBITED AND ANTIBODY-COATED ERYTHROCYTES

1964 ◽  
Vol 47 (3_Suppl) ◽  
pp. S28-S36
Author(s):  
Kailash N. Agarwal
Keyword(s):  
Red Cells ◽  
List Type ◽  
Red Cell

ABSTRACT Red cells were incubated in vitro with sulfhydryl inhibitors and Rhantibody with and without prior incubation with prednisolone-hemisuccinate. These erythrocytes were labelled with Cr51 and P32 and their disappearance in vivo after autotransfusion was measured. Prior incubation with prednisolone-hemisuccinate had no effect on the rate of red cell disappearance. The disappearance of the cells was shown to take place without appreciable intravascular destruction.

Fenofibrate Solid Dispersion for Improving Oral Bioavailability: Preparation, and Characterization and in vivo Evaluation

2020 ◽  
Vol 13 (5) ◽  
pp. 5102-5109
Author(s):  
Venu Madhav K ◽  
Somnath De ◽  
Chandra Shekar Bonagiri ◽  
Sridhar Babu Gummadi
Keyword(s):  
Oral Bioavailability ◽  
Oral Delivery ◽  
Solid Dispersions ◽  
In Vitro Release ◽  
Aqueous Solubility ◽  
Water Soluble ◽  
Scanning Calorimetry ◽  
In Vivo Evaluation

Fenofibrate (FN) is used in the treatment of hypercholesterolemia. It shows poor dissolution and poor oral bioavailability after oral administration due to high liphophilicity and low aqueous solubility. Hence, solid dispersions (SDs) of FN (FN-SDs) were develop that might enhance the dissolution and subsequently oral bioavailability. FN-SDs were prepared by solvent casting method using different carriers (PEG 4000, PEG 6000, β cyclodextrin and HP β cyclodextrin) in different proportions (0.25%, 0.5%, 0.75% and 1% w/v). FN-SDs were evaluated solubility, assay and in vitro release studies for the optimization of SD formulation. Differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD) and scanning electron microscopy (SEM) analysis was performed for crystalline and morphology analysis, respectively. Further, optimized FN-SD formulation evaluated for pharmacokinetic performance in Wistar rats, in vivo in comparison with FN suspension.  From the results, FN-SD3 and FN-SD6 have showed 102.9 ±1.3% and 105.5±3.1% drug release, respectively in 2 h. DSC and PXRD studies revealed that conversion of crystalline to amorphous nature of FN from FT-SD formulation. SEM studies revealed the change in the orientation of FN when incorporated in SDs. The oral bioavailability FN-SD3 and FN-SD6 formulations exhibited 2.5-folds and 3.1-folds improvement when compared to FN suspension as control. Overall, SD of FN could be considered as an alternative dosage form for the enhancement of oral delivery of poorly water-soluble FN.

Evaluation of the In Vivo Acute Toxicity and In Vitro Hemolytic and Immunomodulatory Activities of the Moringa oleifera Flower Trypsin Inhibitor (MoFTI)

2020 ◽  
Vol 27 ◽  
Author(s):  
Leydianne Leite de Siqueira Patriota ◽  
Dayane Kelly Dias do Nascimento Santos ◽  
Bárbara Rafaela da Silva Barros ◽  
Lethícia Maria de Souza Aguiar ◽  
Yasmym Araújo Silva ◽  
...  
Keyword(s):  
Acute Toxicity ◽  
Trypsin Inhibitor ◽  
Hemolytic Activity ◽  
Moringa Oleifera ◽  
Biological Activities ◽  
Hematological Parameters ◽  
Behavioral Alterations ◽  
Female Mice

Background: Protease inhibitors have been isolated from plants and present several biological activities, including immunomod-ulatory action. Objective: This work aimed to evaluate a Moringa oleifera flower trypsin inhibitor (MoFTI) for acute toxicity in mice, hemolytic activity on mice erythrocytes and immunomodulatory effects on mice splenocytes. Methods: The acute toxicity was evaluated using Swiss female mice that received a single dose of the vehicle control or MoFTI (300 mg/kg, i.p.). Behavioral alterations were observed 15–240 min after administration, and survival, weight gain, and water and food consumption were analyzed daily. Organ weights and hematological parameters were analyzed after 14 days. Hemolytic activity of MoFTI was tested using Swiss female mice erythrocytes. Splenocytes obtained from BALB/c mice were cultured in the absence or presence of MoFTI for the evaluation of cell viability and proliferation. Mitochondrial membrane potential (ΔΨm) and reactive oxygen species (ROS) levels were also determined. Furthermore, the culture supernatants were analyzed for the presence of cytokines and nitric oxide (NO). Results: MoFTI did not cause death or any adverse effects on the mice except for abdominal contortions at 15–30 min after administration. MoFTI did not exhibit a significant hemolytic effect. In addition, MoFTI did not induce apoptosis or necrosis in splenocytes and had no effect on cell proliferation. Increases in cytosolic and mitochondrial ROS release, as well as ΔΨm reduction, were observed in MoFTI-treated cells. MoFTI was observed to induce TNF-α, IFN-γ, IL-6, IL-10, and NO release. Conclusion: These results contribute to the ongoing evaluation of the antitumor potential of MoFTI and its effects on other immunological targets.

Chemosensitizing Activity of Histone Deacetylases Inhibitory Cyclic Hydroxamic Acids for Combination Chemotherapy of Lymphatic Leukemia

2018 ◽  
Vol 18 (4) ◽  
pp. 365-371 ◽  
Author(s):  
Denis V. Mishchenko ◽  
Margarita E. Neganova ◽  
Elena N. Klimanova ◽  
Tatyana E. Sashenkova ◽  
Sergey G. Klochkov ◽  
...  
Keyword(s):  
Lipid Peroxidation ◽  
Acute Toxicity ◽  
Histone Deacetylases ◽  
Hydroxamic Acids ◽  
Water Soluble ◽  
Male Rat ◽  
Hybrid Male ◽  
Cyclic Hydroxamic Acids

Background: Anti-tumor effect of hydroxamic acid derivatives is largely connected with its properties as efficient inhibitors of histone deacetylases, and other metalloenzymes involved in carcinogenesis. Objective: The work was aimed to (i) determine the anti-tumor and chemosensitizing activity of the novel racemic spirocyclic hydroxamic acids using experimental drug sensitive leukemia P388 of mice, and (ii) determine the structure-activity relationships as metal chelating and HDAC inhibitory agents. Method: Outbreed male rat of 200-220 g weights were used in biochemical experiments. In vivo experiments were performed using the BDF1 hybrid male mice of 22-24 g weight. Lipid peroxidation, Fe (II) -chelating activity, HDAC fluorescent activity, anti-tumor and anti-metastatic activity, acute toxicity techniques were used in this study. Results: Chemosensitizing properties of water soluble cyclic hydroxamic acids (CHA) are evaluated using in vitro activities and in vivo methods and found significant results. These compounds possess iron (II) chelating properties, and slightly inhibit lipid peroxidation. CHA prepared from triacetonamine (1a-e) are more effective Fe (II) ions cheaters, as compared to CHA prepared from 1- methylpiperidone (2a-e). The histone deacetylase (HDAC) inhibitory activity, lipophilicity and acute toxicity were influenced by the length amino acids (size) (Glycine < Alanine < Valine < Leucine < Phenylalanine). All compounds bearing spiro-N-methylpiperidine ring (2a-e) are non-toxic up to 1250 mg/kg dose, while compounds bearing spiro-tetramethylpiperidine ring (1a-e) exhibit moderate toxicity which increases with increasing lipophility, but not excite at 400 mg/kg. Conclusion: It was shown that the use of combination of non-toxic doses of cisplatin (cPt) or cyclophosphamide with CHA in most cases result in the appearance of a considerable anti-tumor effect of cytostatics. The highest chemosensitizing activity with respect to leukemia Р388 is demonstrated by the CHA derivatives of Valine 1c or 2c.

scholarly journals Development, Characterization and In Vivo Pharmacokinetic Assessment of Rectal Suppositories Containing Combination Antiretroviral Drugs for HIV Prevention

Pharmaceutics ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1110
Author(s):  
Kunal Jhunjhunwala ◽  
Charles W. Dobard ◽  
Sunita Sharma ◽  
Natalia Makarova ◽  
Angela Holder ◽  
...  
Keyword(s):  
Hiv Prevention ◽  
Antiretroviral Drugs ◽  
Water Soluble ◽  
Fixed Dose ◽  
Receptive Anal Intercourse ◽  
On Demand ◽  
Dose Combination ◽  
Rectal Suppositories

Receptive anal intercourse (RAI) contributes significantly to HIV acquisition underscoring the need to develop HIV prevention options for populations engaging in RAI practices. We explored the feasibility of formulating rectal suppositories with potent antiviral drugs for on-demand use. A fixed-dose combination of tenofovir (TFV) and elvitegravir (EVG) (40 mg each) was co-formulated in six different suppository bases (three fat- and three water-soluble). Fat-soluble witepsol H15 and water-soluble polyethylene glycol (PEG) based suppositories demonstrated favorable in vitro release and were advanced to assess in vivo pharmacokinetics following rectal administration in macaques. In vivo drug release profiles were similar for both suppository bases. Median concentrations of TFV and EVG detected in rectal fluids at 2 h were 1- and 2-logs higher than the in vitro IC50, respectively; TFV-diphosphate levels in rectal tissues met or exceeded those associated with high efficacy against rectal simian HIV (SHIV) exposure in macaques. Leveraging on these findings, a PEG-based suppository with a lower dose combination of tenofovir alafenamide (TAF) and EVG (8 mg each) was developed and found to achieve similar rectal drug exposures in macaques. This study establishes the utility of rectal suppositories as a promising on-demand strategy for HIV PrEP and supports their clinical development.

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