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Fractionation of prion protein aggregates by asymmetrical flow field-flow fractionation.

Achieving the successful separation and analysis of amyloid and other large protein aggregates can be a difficult proposition. Field-flow fractionation (FFF) is a flow-based separation method like chromatography; however, FFF is capable of high-resolution separations in the absence of a stationary matrix. Thus, FFF is a relatively gentle technique and is well suited to the task of separating large macromolecules and macromolecular complexes. Flow field-flow fractionation (FlFFF), one of the techniques in the FFF family, has been used to successfully fractionate a wide size range of prion protein aggregates, allowing their subsequent characterization by several biophysical and biochemical methods. The ability to easily adjust the strength of the field used during separation means that FlFFF could be applied to particles ranging from 1 nm to nearly 100 mum in size. This flexibility, coupled with the ability to produce fast, high-resolution separations, makes FFF a potentially valuable tool in the field of amyloid research.

Chemical Fractionation↗

Lactate dehydrogenase associated with the mitochondrial fraction and with a mitochondrial inhibitor--I. Enzyme binding to the mitochondrial fraction.

Rabbit skeletal muscle mitochondrial fraction shows LDH activity (212 +/- 43 U/g pellet). The majority of the mitochondrial enzyme was solubilized by washing with 0.15 M NaCl, pH 6, or by ultrasonic treatment in the same medium. It was also solubilized on increasing the ionic strength and the pH of the medium. Cytosoluble LDH was observed to bind in vitro to the particulate fraction and the enzyme bound was a sigmoidal function of the amount of soluble enzyme added. The bound enzyme is less active than the soluble one. Kinetically, active mitochondrial fraction or in vitro bound enzyme showed non-hyperbolic behavior which is different from the bi-bi sequential-ordered type mechanism of the soluble enzyme.

Animals↗

In vitro bioactivity-guided fractionation and characterization of polyphenolic inhibitory fractions from Acacia nilotica (L.) Willd. ex Del.

The present study was undertaken to evaluate antimutagenic and cytotoxic effects of different extracts/fractions of Acacia nilotica prepared by maceration method. The potency order of different extracts was more or less similar in Ames assay as well as in cytotoxic assay. Considering the maximum potential of acetone extract in both the assays, the studies were initiated to fractionate this extract. Two pure fractions, namely AN-1 and AN-2, were obtained from acetone extract, of which AN-2 was found to be of gallic acid and AN-1 fraction is still to be identified. In conclusion, the antimutagenic and cytotoxic activities exhibited by acetone extract may partially be ascribed to the presence of gallic acid and other polyphenols.

Acacia↗

Reconstitution of Na+/H(+)-antiporter of bovine renal brush-border membrane into proteoliposomes and detection of a 110 kDa protein cross-reactive with antibodies against a human Na+/H(+)-antiporter partial peptide in antiport-active fractions after partial fractionation.

Bovine renal brush-border membranes were solubilized by 1.6% sodium cholate. Na+/H(+)-antiporter was recovered in the supernatant after centrifugation at 160,000 x g for 1 h and was successfully reconstituted into proteoliposomes by a cholate-dialysis procedure. The reconstituted Na+/H(+)-antiporter showed a pH-gradient dependent and amiloride-sensitive 22Na+ uptake very similar to that of brush-border membrane vesicles. Factors affecting the efficiency of reconstitution as well as the stability of the solubilized antiporter at various temperatures were studied. Sodium cholate-solubilized brush-border membrane proteins were fractionated by Sephacryl S-400 and DEAE-Toyopearl chromatography, and fractions containing reconstitutively active Na+/H(+)-antiporter were identified. A 110 kDa peptide cross-reactive with a polyclonal antibody against a C-terminal peptide (22-amino acid residues) of human Na+/H(+)-antiporter was consistently found on the immunoblot of the active fractions. A closely similar peptide was also detected in human placental membranes by this antibody. These results strongly suggest that the 110 kDa protein is responsible for Na+/H(+)-antiporter activity.

Animals↗

Di (2-ethylhexyl)phthalate content of plasma fractions prepared by low temperature ethanol (Cohn) fractionation.

Plasma pools, prepared from time-expired blood stored in plastic packs, were analysed for DEHP content and levels ranging from 0.78 to 7.42 mh DEHP/100 ml plasma obtained. The DEHP content of the Cohn fractions prepared from such plasma pools was estimated. Only very low levels of DEHP were found in the four therapeutically useful fractions and high levels in the discard fractions III and IV.

Adult↗

Freedom from transmission of hepatitis-B of gamma-globulin and heat-inactivated plasma protein fraction prepared from contaminated human plasma by fractionation with solid-phase polyelectrolytes.

Plasma contaminated with hepatitis B surface antigen (HBsAg) and shown by others to be infectious when injected in a dilution of 1:1,000,000 in chimpanzees, was fractionated by a solid-phase polyelectrolyte (PE) procedure for its content of plasma protein fraction (PPF) and gamma-globulin (immune serum globulin; ISG). Quantitative Ausria II radioimmunoassays showed that nearly half the HBsAg was bound by the PE and could be eluted at low pH, while the rest was found in the heat-inactivated PPF. When the ISG was concentrated to 16%, the 13 mg/kg (comparable to a human dose) was injected intramuscularly in 6 chimpanzees, or when the PPF was heated at 60 degrees C for h and injected intravenously in 2 chimpanzees, there was no clinical or laboratory evidence of hepatitis B infection after 12 months, although 1 chimp of 2 who received the same material showed a borderline positive anti-HBsAg antibody result on one of 52 weekly serum samples. Since the new PE fractionation method is essentially nondenaturing, and simpler than the classical ethanol procedures, it was important to establish the noninfectivity of the final products.

Adsorption↗

Randomized trials on altered fractionation in head and neck cancer radiotherapy with conventional fractionation as control arm: another lap to go.

The Authors present a review of randomized trials on non conventional fractionation in head and neck cancer radiotherapy with conventional fractionation as control arm. Hyperfractionation was studied in 5 trials, accelerated hyperfractionation in 4 trials and accelerated fractionation in 3 trials. Furthermore, the reviews of eminent Authors dealing with the above mentioned trials are summarized. In spite of improved local control rate reported with hyperfractionation, non conventional radiotherapy schedules are not yet recommended as routine clinical practice, but all the radiation oncologists are Invited to join trials on this subject.

Dose Fractionation, Radiation↗

[Separation of Shigella toxins into fractions differing in biological activity and characteristics of the fractions inducing penetration in avirulent strains].

The results obtained in the study of the biological activity of the lysates of 14 Sh. flexneri and Sh. sonnei strains differing in their virulence are presented. In the lysates of the virulent cultures 2 kinds of biological activity corresponding to the fractions of peaks I and II could be detected: one fraction possessed HeLa toxicity, the other fraction possessed enterotoxic activity. The avirulent nonpenetrating mutants had no HeLa toxicity, but retained their capacity for producing factors similar to enterotoxin. When added to a nontoxic dose, HeLa toxin produced by the virulent Shigella strains enhanced the penetration capacity of the virulent strains and imparted this capacity to the avirulent cultures of a homologous Shigella species.

Bacterial Toxins↗

Transient increases of growth fraction during fractionated radiation therapy for cervical carcinoma. Ki-67 and PC10 immunostaining.

BACKGROUND: The Ki-67 and PC10 indexes are consistent with the growth and S-phase fractions, respectively. METHODS: Eighty-three biopsy specimens from 18 patients with cervical squamous cell carcinoma were examined before and during fractionated radiation therapy (RT), using an immunohistochemical method. RESULTS: The 18 patients were divided into two groups according to the Ki-67 index before RT; those with values of less than 42% (Group A; n = 11) and those with values of 42% or more (Group B; n = 7). The Ki-67 index in Group A increased approximately twofold at radiation doses of 5.4-9 Gy compared with values before RT. The Ki-67 index in Group B, which increased slightly at doses of 5.4-9 Gy, decreased by approximately one-fifth at a dose of 27 Gy, compared with the value before RT. The PC10 indexes in both groups showed little change to doses of 5.4-9 Gy. The mitotic indexes were less than 1% before RT and decreased to a minimum with doses of 18-27 Gy. There was no correlation between the Ki-67 and PC10 indexes before or during RT. CONCLUSION: In cancer tissues with a low growth fraction before RT, radiation doses of 5.4-9 Gy produced increases in the numbers of cycling cancer cells in the G1 or G2 phases. This transient increase possibly was attributable to the combined effects of the recruitment phenomenon and G1 or G2 block.

Adult↗

Determination of the free fraction and relative free fraction of drugs strongly bound to plasma proteins.

This report describes a new method for the determination of protein binding and relative protein binding (ratio of f(u) for different species) for compounds strongly bound to proteins. The method used is based on the distribution of the drug in plasma water, plasma proteins, and blood cells. Incubations were performed in diluted plasma. In diluted plasma, the erythrocyte/plasma distribution was determined with greater precision than in undiluted plasma. Formulae were derived for calculating f(u) in undiluted plasma based on the f(u) values determined in diluted plasma. These formulae are also valid in the event of more than one independent binding site in plasma. All incubations with plasma of different species were performed using rat erythrocyte suspensions, thereby making it possible for relative f(u) values in different species to be calculated without knowing the absolute free fractions. This method avoids the determination of the erythrocyte/buffer distribution in cases where it is sufficient to know relative f(u) values (e.g., exposure comparisons). Relative protein binding can also be quantified for compounds that tend to adsorb to surfaces of vials or test tubes, thus avoiding errors caused by adsorption when quantifying the drug in a protein-free aqueous solution. This method was validated by making comparisons of free fraction values obtained by the method herein described with those obtained by either ultrafiltration or equilibrium dialysis for two compounds that bind predominantly to albumin and another compound that binds to alpha(1)-acid glycoprotein. The results confirm our method produces identical free fractions in comparison with other established techniques. In addition, the range of applications of our method is much wider.

Animals↗

Inhibition of the mutagenicity of cooked-beef basic fraction by its acidic fraction.

By using the Salmonella/microsome system, it was found that the activity of mutagens present in the basic fraction of cooked-ground-beef was completely suppressed by addition of the acidic fraction obtained from the cooked-beef. The suppression was ascribable to the presence of oleic acid in the acidic fraction. This finding indicates that no, or diminished, mutagenicity would be found in materials containing fat.

Animals↗

Analysis of Creutzfeldt-Jakob disease infectious fractions by gel permeation chromatography and sedimentation field flow fractionation.

Gel permeation chromatography and sedimentation field flow fractionation (SF3) were used to further analyze highly infectious fractions from Creutzfeldt-Jakob disease (CJD) infected hamster brain. These analyses defined the relative molecular mass and physical size of the Creutzfeldt-Jakob disease (CJD) agent with greater precision than previously possible. Highly purified disaggregated fractions yielded single, homogeneous Gaussian peaks with both methods. The relevant analytical peaks contained protein-nucleic acid complexes with an M(r) of approximately 1.5 x 10(7) daltons and a mean radius of approximately 30 nm. The experimental evidence further solidifies the concept of an infectious agent that resembles a viral core rather than a simple protein.

Animals↗

Differences in repopulation kinetics in mouse skin during split course multiple fractions per day (MFD) or daily fractionated irradiations.

The influence of protraction and distribution of irradiation as a function of time on the repopulation kinetics of mouse skin have been evaluated. Twenty fractions have been given either daily for 5 days per week during 4 weeks, or thrice a day to 10 irradiations in 3 days, repeated after a rest period of 19 days, resulting also in an overall time of 4 weeks. The acute skin reaction was scored. It was found that the split course multiple fractions per day (MFD) schedule induced less skin reaction than continuous daily fractionation, which was mainly attributable to recovery of skin damage during the rest period. Therefore, it can be postulated that the repopulation of the surviving clonogenic epidermal cells is less efficient during continuous daily irradiation than during split course MFD schedule given in the same overall treatment time.

Animals↗

Single fraction per day versus two fractions per day versus radiochemotherapy in the treatment of head and neck cancer.

From January 1978 to January 1988, 859 patients with T3-T4, NO-3, MO were randomly allocated to receive either: Group A--60Co 60, 60 Gy in 30 fractions; Group B--60Co, 70.4 Gy in 64 fractions; Group C--60Co, 60 Gy in 30 fractions plus chemotherapy (5 Fu, 250 mg/m2/IV every 2 days). Chemotherapy and radiotherapy were combined simultaneously. The average age was 56 years; the male/female ratio was 802/57. Median performance status (ECOG scale) was 1 (range 0-2). The TNM distribution as UICC criteria was T3 529 patients; T4 330 patients; No 217 patients; N1 52 patients; N2 319 patients; and N3 271 patients. The primary sites were nasopharynx 92, oral cavity 252, hypopharynx 119, larynx 310, and others (sinuses and unknown primary)86. Complete response was achieved in 188/277 patients in Group A (67.8%), 254/282 patients in Group B (90%), and 289/300 in Group C (96.3%). All patients were followed and statistical analysis shows a significant improvement in median duration of response, as well as survival for Groups B and C compared with Group A. No significant differences were seen between Group B and C. The acute toxicity was mucositis, skin toxicity, bone marrow depression. A mean temporary weight loss of 4.9 Kg was observed with a range of 2.3-10.5 Kg.

Adult↗

Isolation of the C3 complement component and its C3d subunit from IY-1 fraction of Cohn's fractionation of human plasma.

C3 complement component and its C3d subunit were isolated from the IY-1 Cohn's fraction, which is the waste of industrially produced albumin and immunoglobulins. The first step was the fractionation of precipitate IY-1 by polyethylene glycol (PEG) 4000 to a final concentration of 16% PEG. The precipitate formed was separated by centrifugation. The supernatant contained the C3d subunit of C3, and the redissolved 16% PEG precipitate contained the C3 component. Then the supernatant and the dissolved precipitate were subjected to anion-exchange chromatography on DEAE-Toyopearl 650 M. In the last step fractions containing C3 and C3d concentrated by ultrafiltration were chromatographed on Sephacryl S-200.

Blood Proteins↗

Two-fraction and three-fraction continuous simulated moving bed separation of nucleosides.

A new experimental set-up and a new simulated moving bed (SMB) operation are presented in this work. A desktop SMB unit developed as a modification of the commercial AKTA explorer working platform has been utilized for the separation of different mixtures of nucleosides. Both two fraction and three fraction SMB separations have been carried out, the latter made possible by the adoption of a new SMB configuration and operating mode (three fraction SMB, 3F-SMB, operation). Experiments demonstrate the feasibility of the 3F-SMB operation, and confirm the trends predicted based on considerations about retention of the components to be separated along the unit.

Chromatography↗

Allogeneic bone marrow transplantation using stem cells fractionated by lectins: VI, in vitro analysis of human and monkey bone marrow cells fractionated by sheep red blood cells and soybean agglutinin.

A procedure was developed for the isolation from human bone marrow of a cell fraction enriched for haematopoietic precursors and depleted of T lymphocytes. T cells are eliminated from bone marrow by rosetting with sheep red blood cells, followed by differential agglutination of residual T lymphocytes in the non-rosetting population by the lectin, soybean agglutinin. The fraction unagglutinated by the lectin contains a high proportion of colony-forming cells and non detectable T cell alloreactivity in vitro. Similar results were obtained with monkey bone-marrow cells, suggesting that monkeys can be used for evaluation of this fractionation technique for bone-marrow transplantation across histocompatibility barriers.

Animals↗

Multiple small fractions per day versus conventional fractionation. Comparison of normal tissue reactions and effect on breast carcinoma.

Hyperfractionation (3 fractions of about 1.0 Gy/day) and conventional fractionation were compared in two studies. In the first, the acute skin reactions, erythema and pigmentation, and the development of telangiectasia were analysed on postoperatively irradiated bilateral parasternal fields in patients with breast carcinoma. In the second study, the tumour effect in patients with inoperable breast carcinoma was investigated under conditions of equivalent normal tissue reactions for both fractionation schedules. With hyperfractionation the late-responding normal tissue was spared relative to the acutely responding normal tissue about 5% in absorbed dose. Concerning the therapeutic effect on adenocarcinoma of the breast 3 X 1.0 Gy/day was not better than 1 X 2.4 Gy/day. These daily doses resulted in equivalent late effects as was predicted from the normal tissue study.

Breast Neoplasms↗