scholarly journals Efficacy of Hospital Cleaning Agents and Germicides Against EpidemicClostridium difficileStrains

2007 ◽  
Vol 28 (8) ◽  
pp. 920-925 ◽  
Author(s):  
Warren N. Fawley ◽  
Sarah Underwood ◽  
Jane Freeman ◽  
Simon D. Baines ◽  
Katie Saxton ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Spore Form ◽  
Cleaning Agent ◽  
Cleaning Agents ◽  
A Cell ◽  
The Mean ◽  
Sporulation Rate ◽  
Hospital Cleaning

Objective.To compare the effects of hospital cleaning agents and germicides on the survival of epidemicClostridium difficilestrains.Methods.We compared the activity of and effects of exposure to 5 cleaning agents and/or germicides (3 containing chlorine, 1 containing only detergent, and 1 containing hydrogen peroxide) on vegetative and spore forms of epidemic and non-epidemicC. difficilestrains (3 of each). We carried out in vitro exposure experiments using a human fecal emulsion to mimic conditions found in situ.Results.Cleaning agent and germicide exposure experiments yielded very different results forC. difficilevegetative cells, compared with those for spores. Working-strength concentrations of all of the agents inhibited the growth ofC. difficilein culture. However, when used at recommended working concentrations, only chlorine-based germicides were able to inactivateC. difficilespores.C. difficileepidemic strains had a greater sporulation rate than nonepidemic strains. The mean sporulation rate, expressed as the proportion of a cell population that is in spore form, was 13% for all strains not exposed to any cleaning agent or germicide, and it was significantly increased by exposure to cleaning agents or germicides containing detergent alone (34%), a combination of detergent and hypochlorite (24%), or hydrogen peroxide (33%). By contrast, the mean sporulation rate did not change substantially after exposure to germicides containing either a combination of detergent and dichloroisocyanurate (9%) or dichloroisocyanurate alone (15%).Conclusions.These results highlight differences in the activity of cleaning agents and germicides againstC. difficilespores and the potential for some of these products to promote sporulation.

scholarly journals Chemical Cleaning of Ultrafiltration Membrane Fouled by Humic Substances: Comparison between Hydrogen Peroxide and Sodium Hypochlorite

2019 ◽  
Vol 16 (14) ◽  
pp. 2568 ◽  
Author(s):  
Kai Li ◽  
Shu Li ◽  
Tinglin Huang ◽  
Chongzhe Dong ◽  
Jiawei Li ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Humic Substances ◽  
Sodium Hypochlorite ◽  
Alkaline Condition ◽  
Chemical Cleaning ◽  
H2o2 Treatment ◽  
Cleaning Agent ◽  
Cleaning Agents ◽  
Cleaning Efficacy ◽  
By Products

Chemical cleaning is indispensable for the sustainable operation of ultrafiltration (UF) system in water and wastewater treatment. Sodium hypochlorite (NaClO) is an established cleaning agent for membranes subject to organic and microbial fouling, but concerns have been raised about the generation of toxic halogenated by-products during NaClO cleaning. Hydrogen peroxide (H2O2) is a potential “green” cleaning agent that can avoid the formation of halogenated by-products. In this work, cleaning efficacy of H2O2 and NaClO for UF membrane fouled by humic substances (HS) was evaluated under a wide pH range, and change of HS’s properties due to reaction with cleaning agents was examined. The cleaning efficacy of H2O2 was lower than that of NaClO at pH 3–9, but it increased to a level (91.4%) comparable with that of NaClO at pH 11. The extents of changes in properties and fouling potential of HS due to reacting with cleaning agents were consistent with their cleaning efficacy. H2O2 treatment at pH 11 significantly increased negative charge of HS molecules, decomposed high-MW molecules, and reduced its fouling potential. Therefore, considering treatment/disposal of cleaning waste and cleaning efficacy, H2O2 cleaning under strong alkaline condition can be a good choice for HS-fouled membrane.

Divisions cellulaires au niveau de l'épiderme de l'hypocotyle du lin (Linum usitatissimum) cultivé in vitro

1985 ◽  
Vol 63 (10) ◽  
pp. 1691-1695 ◽  
Author(s):  
M. Sqalli ◽  
H. Chlyah
Keyword(s):  
Cell Division ◽  
Culture Cell ◽  
Epidermal Cells ◽  
Isolated Cells ◽  
Initiation And Propagation ◽  
A Cell ◽  
The Mean ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes

A study of the initiation and propagation of cell divisions in the epidermis of flax hypocotyl segments cultured in vitro was made using surface observations (light and scanning electron microscopes) as well as transverse and longitudinal sections. Epidermal cells were of two types: long, narrow cells and short, wide cells. The latter, less numerous, rarely participated in cell division. Nuclear activation and the first mitoses appeared very early (after 4–8 h of culture). Cell division began in isolated cells and spread progressively to surrounding cells arranged transversely. At 24 h, approximately 50 cells in division or newly divided were observed on an epidermal strip of 10 × 2 mm composed of about 8000 original cells. At 48 h, about 110 cells had divided forming 22 division centers; 26 prophase, 10 metaphase, and 7 telophase figures were observed. The mean number of original cells which participated in the formation of a cell division center was three at 12 h, five at 72 h, with no increase thereafter. The percentage of cells in mitosis or already divided remained low (1.9%) in relation to the total number of epidermal cells. For 22 division centers, only 7 would participate in vegetative bud formation.

scholarly journals STUDIES ON THE RIGOR RESULTING FROM THE THAWING OF FROZEN FROG SARTORIUS MUSCLE

1950 ◽  
Vol 33 (5) ◽  
pp. 563-577 ◽  
Author(s):  
S. V. Perry
Keyword(s):  
Hydrogen Peroxide ◽  
Iodoacetic Acid ◽  
Sartorius Muscle ◽  
Fixed Length ◽  
Frog Sartorius Muscle ◽  
Vitro Effect ◽  
Resting Muscle ◽  
Frog Sartorius

1. The rigor which takes place when completely frozen frog sartorius muscle is thawed ("thaw rigor"), is accompanied by a decrease in length of 70 per cent and a loss in weight of 35 per cent, whether the muscle is frozen in the resting or the exhausted condition, or during isometric tetanus. Muscle tetanized to maximal shortening shows a loss in weight of 25 per cent on thawing. 2. A load of 8 gm. is sufficient to prevent the decrease in length on thawing, but after its removal the muscle will shorten almost to the normal extent. 3. Inhibitors such as azide, cyanide, 2:4 dinitrophenol, p-chloromercuribenzoate, Cu, and hydrogen peroxide, when used for periods not exceeding 1 hour, have little effect on the shortening; although in some cases these poisons render the muscle inexcitable. 4. Muscles poisoned with iodoacetic acid and stimulated to exhaustion, or maintained at fixed length in nitrogen, show little or no shortening on thawing. ATP can produce shortening in the muscles in which it has been prevented. 5. The phenomenon is considered to be due to an in situ synaeresis of the actomyosin of the myofibrils. As a result of the disorganisation of the muscle protoplasm produced by the freezing and subsequent thawing, the ATP, which must be bound or localized in the resting muscle, can act on the myofibril in a similar manner to its in vitro effect on the actomyosin thread.

scholarly journals Study of DNA damage induced by dental bleaching agents in vitro

2006 ◽  
Vol 20 (1) ◽  
pp. 47-51 ◽  
Author(s):  
Daniel Araki Ribeiro ◽  
Mariângela Esther Alencar Marques ◽  
Daisy Maria Fávero Salvadori
Keyword(s):  
Hydrogen Peroxide ◽  
Dna Damage ◽  
Comet Assay ◽  
Single Cell ◽  
Chinese Hamster ◽  
Dental Bleaching ◽  
Dna Breakage ◽  
The Mean ◽  
Positive Controls

Dental bleaching is a simple and conservative procedure for aesthetic restoration of vital and non-vital discolored teeth. Nevertheless, a number of studies have demonstrated the risk of tissue damage from the contact of these agents with the oral mucosa. In the current study, the genotoxic potential associated with exposure to dental bleaching agents was assessed by the single cell gel (comet) assay in vitro. Chinese hamster ovary (CHO) cells in vitro were exposed to six commercial dental bleaching agents (Clarigel Gold - Dentsply; Whitespeed - Discus Dental; Nite White - Discus Dental; Magic Bleaching - Vigodent; Whiteness HP - FGM and Lase Peroxide - DMC). The results pointed out that all dental bleaching agents tested contributed to DNA damage as depicted by the mean tail moment, being the strongest effect observed with the highest dose of hydrogen peroxide (Whiteness HP and Lase Peroxide, at a 35% concentration). On the other hand, Magic Bleaching (Vigodent) induced the lowest level of DNA breakage. Negative and positive controls displayed absence and presence of DNA-damaging, respectively. Taken together, these results suggest that dental bleaching agents may be a factor that increases the level of DNA damage. A higher concentration of hydrogen peroxide produced higher noxious activities in the genome as detected by single cell gel (comet) assay.

A new succinylcholine-based assay of plasma cholinesterase.

1984 ◽  
Vol 30 (2) ◽  
pp. 192-195 ◽  
Author(s):  
M H Abernethy ◽  
P M George ◽  
V E Melton
Keyword(s):  
Hydrogen Peroxide ◽  
Enzyme Activity ◽  
Plasma Cholinesterase ◽  
Choline Oxidase ◽  
Rate Of Hydrolysis ◽  
The Mean ◽  
Variant Enzyme ◽  
Hydrolysis Of

Abstract We describe a new method for measuring the in vitro rate of hydrolysis of the muscle relaxant succinylcholine. This substrate is hydrolyzed by plasma cholinesterase (EC 3.1.1.8). The resulting choline is determined by measuring the hydrogen peroxide formed on its oxidation by choline oxidase (EC 1.1.3.17). This is done by use of phenol and aminoantipyrine coupled to peroxidase, and yields an intense chromophore, Amax 500 nm. The assay requires 0.1 mL of plasma, and is precise and specific. The CV was 2.7% within run, 7.3% between run. For the usual (U variant) enzyme the Km is 53 mumol/L. Enzyme activity is removed by anticholinesterase antiserum, and is inhibited by dibucaine with a Ki of 2 mumol/L. Ten samples can be assayed in duplicate in an hour. This method is suited to routine use in any laboratory that has a simple spectrophotometer. The mean activity in 11 individuals with the cholinesterase phenotype UU was 105 U/L, for seven UA heterozygotes 61 U/L, and for three AA homozygotes 4 U/L. To the extent allowed by extrapolation from in vitro to in vivo results, this method should increase diagnostic accuracy and may directly predict duration of succinylcholine-induced apnea.

scholarly journals Reconstitution and visualization of HIV-1 capsid-dependent replication and integration in vitro

Science ◽  
2020 ◽  
Vol 370 (6513) ◽  
pp. eabc8420 ◽  
Author(s):  
Devin E. Christensen ◽  
Barbie K. Ganser-Pornillos ◽  
Jarrod S. Johnson ◽  
Owen Pornillos ◽  
Wesley I. Sundquist
Keyword(s):  
Cell Extract ◽  
Free System ◽  
Double Stranded Dna ◽  
A Cell ◽  
Dna Ends ◽  
Hiv 1 ◽  
Target Plasmid

During the first half of the viral life cycle, HIV-1 reverse transcribes its RNA genome and integrates the double-stranded DNA copy into a host cell chromosome. Despite progress in characterizing and inhibiting these processes, in situ mechanistic and structural studies remain challenging. This is because these operations are executed by individual viral preintegration complexes deep within cells. We therefore reconstituted and imaged the early stages of HIV-1 replication in a cell-free system. HIV-1 cores released from permeabilized virions supported efficient, capsid-dependent endogenous reverse transcription to produce double-stranded DNA genomes, which sometimes looped out from ruptured capsid walls. Concerted integration of both viral DNA ends into a target plasmid then proceeded in a cell extract–dependent reaction. This reconstituted system uncovers the role of the capsid in templating replication.

Differences in microbial fermentation of barley straw induced by its treatment with anhydrous ammonia

1997 ◽  
Vol 65 (1) ◽  
pp. 111-119 ◽  
Author(s):  
M. Fondevila ◽  
G. Muñoz ◽  
C. Castrillo ◽  
F. Vicente ◽  
S. M. Martín-Orúe
Keyword(s):  
Ammonia Nitrogen ◽  
Gas Production ◽  
Barley Straw ◽  
Microbial Fermentation ◽  
Rumen Degradation ◽  
Rumen Ph ◽  
The Media ◽  
The Mean

AbstractThe effect of ammonia treatment of straw on both the rumen environment and the extent of its microbial fermentation was studied. Four rumen cannulated sheep were randomly given 700 g/day of untreated straw plus urea (US), ammonia-treated straw (TS) and alfalfa hay (AH) in a change-over design with three periods. Rumen pH was lower and ammonia-nitrogen and total volatile fatty acid (VFA) concentrations were higher (P < 0·001) with AH than with US or TS. With the straw diets, TS promoted a lower pH than US (P < 0·05), but differences were less than 0·3 units and the mean pH was never below 6·5. There were no differences between the straw diets in ammonia-nitrogen or VFA concentration (P > 0·05). When untreated barley straw (BS) and treated straw (TS) were incubated in situ disappearance of dry matter (dDM) at 12, 24 and 48 h (P < 0·01) and neutral-detergent fibre (dNDF) at 48 h (P < 0·001) were higher with TS. In vitro incubation showed a higher gas production with TS only after 36 h (P < 0·05) whereas gas from BS fermentation was higher up to 14 h (P < 0·05). Among diets, dDM, dNDF and gas production with US were numerically higher than with TS or AH throughout, although few significant differences were observed, except for a higher dDM at 12 (P < 0·01) and 24 (P < 0·10) h and a higher dNDF at 12 h (P < 0·10). Particle-associated enzymes were extracted from BS and TS incubated in the rumen for 4, 8, 22 and 24 h. Results ofxylanase and cellulase activities support those of straw incubation, with a drop between 4 and 8 h in TS diet. The concentration of residual phenolics per unit of incubated straws after 12 and 24 h show that phenolics release to the media was higher with the TS diet. Daily changes of phenolic concentration into rumen liquid was also higher with TS than with US (P < 0·001). The increased release of straw phenolics by ammoniation reduced the potential for rumen degradation of straw, mainly in the first hours of the fermentation period.

Comparison of the Efficacy of a Hydrogen Peroxide Dry-Mist Disinfection System and Sodium Hypochlorite Solution for Eradication of Clostridium difficile Spores

2009 ◽  
Vol 30 (6) ◽  
pp. 507-514 ◽  
Author(s):  
F. Barbut ◽  
D. Menuet ◽  
M. Verachten ◽  
E. Girou
Keyword(s):  
Hydrogen Peroxide ◽  
Sodium Hypochlorite ◽  
Environmental Contamination ◽  
Bacterial Count ◽  
Sodium Hypochlorite Solution ◽  
Hypochlorite Solution ◽  
Colony Forming Units ◽  
In Situ Experiments

Objective.To compare a hydrogen peroxide dry-mist system and a 0.5% hypochlorite solution with respect to their ability to disinfect Clostridium difficile-contaminated surfaces in vitro and in situ.Design.Prospective, randomized, before-after trial.Setting.Two French hospitals affected by C. difficile.Intervention.In situ efficacy of disinfectants was assessed in rooms that had housed patients with C. difficile infection. A prospective study was performed at 2 hospitals that involved randomization of disinfection processes. When a patient with C. difficile infection was discharged, environmental contamination in the patient's room was evaluated before and after disinfection. Environmental surfaces were sampled for C. difficile by use of moistened swabs; swab samples were cultured on selective plates and in broth. Both disinfectants were tested in vitro with a spore-carrier test; in this test, 2 types of material, vinyl polychloride (representative of the room's floor) and laminate (representative of the room's furniture), were experimentally contaminated with spores from 3 C. difficile strains, including the epidemic clone ribotype 027-North American pulsed-field gel electrophoresis type 1.Results.There were 748 surface samples collected (360 from rooms treated with hydrogen peroxide and 388 from rooms treated with hypochlorite). Before disinfection, 46 (24%) of 194 samples obtained in the rooms randomized to hypochlorite treatment and 34 (19%) of 180 samples obtained in the rooms randomized to hydrogen peroxide treatment showed environmental contamination. After disinfection, 23 (12%) of 194 samples from hypochlorite-treated rooms and 4 (2%) of 180 samples from hydrogen peroxide treated rooms showed environmental contamination, a decrease in contamination of 50% after hypochlorite decontamination and 91% after hydrogen peroxide decontamination (P < .005). The in vitro activity of 0.5% hypochlorite was time dependent. The mean (±SD) reduction in initial log10 bacterial count was 4.32 ± 0.35 log10 colony-forming units after 10 minutes of exposure to hypochlorite and 4.18 ± 0.8 logl0 colony-forming units after 1 cycle of hydrogen peroxide decontamination.Conclusion.In situ experiments indicate that the hydrogen peroxide dry-mist disinfection system is significantly more effective than 0.5% sodium hypochlorite solution at eradicating С difficile spores and might represent a new alternative for disinfecting the rooms of patients with C. difficile infection.

scholarly journals Variability of Three Isolates of Botrytis cinerea Affects the Inhibitory Effects of Calcium on this Fungus

2000 ◽  
Vol 90 (7) ◽  
pp. 769-774 ◽  
Author(s):  
Catherine O. Chardonnet ◽  
Carl E. Sams ◽  
Robert N. Trigiano ◽  
William S. Conway
Keyword(s):  
Botrytis Cinerea ◽  
Mycelial Growth ◽  
Dna Analysis ◽  
Epidemiological Studies ◽  
Inhibitory Effects ◽  
Apple Cultivars ◽  
Sporulation Rate ◽  
Polygalacturonase Activity

Botrytis cinerea is an economically important pathogen. Epidemiological studies are difficult because of the genetic variability within this species. The objectives of this work were to study the variability and to compare the inhibitory effects of Ca on three isolates of B. cinerea from decayed apple (B) and grape (C and C77:4). Among these isolates, B had the least radial growth but had a sporulation rate 40% higher than that of both C77:4 and C. In situ, isolate C incited the largest decay area in the fruit of two of four apple cultivars examined and had the highest polygalacturonase activity in vitro. Maximum mycelial growth was reached with CaCl2 at 1 g liter-1 for isolates B and C77:4 and at 4 g liter-1 for isolate C. Calcium (CaCl2) inhibited polygalacturonase activity at 1 g liter-1 for C and C77:4 and at 16 g liter-1 for B. Calcium infiltration reduced decay caused by all three isolates by three to five times. Mycelial DNA analysis showed that 42% of the character loci scored were polymorphic and the greatest similarities were found between B and C77:4. These results support the evidence that the biological and statistical variability in research can be affected by the B. cinerea isolate selected. Despite this variation, Ca treatment of apples reduced decay caused by all three Botrytis cinerea isolates.

scholarly journals In vitro estimation of rumen fermentable organic matter using rumen fluid and a cell free preparation of rumen fluid

1994 ◽  
Vol 42 (4) ◽  
pp. 343-356 ◽  
Author(s):  
J.W. Cone ◽  
A.H. Van Gelder ◽  
E.T. Veerman ◽  
A.M. Van Vuuren
Keyword(s):  
Organic Matter ◽  
Rumen Fluid ◽  
Good Prediction ◽  
Feed Composition ◽  
In Vitro Methods ◽  
In Situ Method ◽  
A Cell

The amount of microbial protein leaving the rumen is considered as a function of the amount of rumen-fermentable organic matter (FOM) in the rumen. FOM can be calculated using tables, or estimated by in situ incubation, but both methods have some drawbacks. In vitro methods were therefore developed to estimate FOM, using fresh rumen fluid or a cell-free preparation of rumen fluid. Results were compared with the in situ method and a method using chemical feed composition. The in vitro methods gave a good prediction of the in situ estimation of FOM for the majority of feeds. For some feeds rich in starch or fat, the correlation was poor. Because no in vivo data of FOM were available, it could not be determined whether the in vitro or in situ methods gave false results. However, arguments suggest that the in situ method is not suitable for some feeds.

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