Comparative mycobactericidal efficacy of chemical disinfectants in suspension and carrier tests

The efficacy of nine disinfectants on Mycobacterium smegmatis was tested in the presence of sputum, using quantitative suspension and carrier tests. Glutaraldehyde, povidone iodine, and chlorhexidine gluconate produced at least a 6-log10 reduction in CFU in all tests. Four disinfectants (sodium dichloroisocyanurate, phenol, ethanol, and sodium hypochlorite) were not as effective in the carrier tests as in the suspension tests; this difference ranged from a 1- to a 5-log10 reduction in CFU. The efficacy of ethanol and sodium hypochlorite was further reduced (3- and 1-log10 reductions in CFU, respectively) in the presence of sputum. The quaternary ammonium compound and iodophor were ineffective in all tests. The findings of this study demonstrate the need for a quantitative carrier test such as the one presented here.     

Studies on prolyl endopeptidase from shakashimeji (Lyophyllum cinerascens): purification and enzymatic properties

High prolyl endopeptidase (post-proline cleaving enzyme) [EC 3.4.21.26] activity was detected in fruit bodies of shakashimeji (Lyophyllum cinerascens), tsukuritake (mushroom: Agaricus bisporus), hirohachichitake (Lactarius hygrophoroides), and yaburebenitake (Russula lepida) which belong to the genus Basidiomycetes. Cell-free extract of shakashimeji showed high activities of proline iminopeptidase and arylamidase as well as prolyl endopeptidase. The prolyl endopeptidase was purified from the extract of shakashimeji by sequential chromatographies on DEAE-Toyopearl, DEAE-Sephadex and hydroxyapatite, and high-performance liquid chromatography with a DEAE-5PW column. The purified enzyme was homogeneous as judged by disc gel electrophoresis. The enzyme was most active at pH 6.8 as checked with Z-Gly-Pro-beta-naphthylamide as a substrate and was stable in the range of pH 5.8-7.4. The isoelectric point of the enzyme was 5.2 and the molecular weight was estimated to be 76,000 by gel filtration on Sephadex G-150 and by sodium dodecyl sulfate (SDS) gel electrophoresis, suggesting that the enzyme was a monomer. The enzyme was completely inhibited by diisopropyl fluorophosphate (DFP), Z-Gly-Pro-CH2Cl, and Z-Pro-prolinal, while it was not inhibited by p-chloromercuribenzoate (PCMB), phenylmethylsulfonyl fluoride (PMSF), or metal chelators. It was estimated that at least five subsites were concerned with the enzyme-substrate binding. Among them, the S1, S2, and S1' sites showed high stereospecificity, as in mammalian, microbial, and plant enzymes. The enzyme hydrolyzed TRH at the carboxyl side of the proline residue. The mushroom enzyme, that was sensitive to DFP, Z-Pro-prolinal, and Z-Gly-Pro-CH2Cl, but not to PCMB, were quite similar in characteristics to the Flavobacterium enzyme.(ABSTRACT TRUNCATED AT 250 WORDS)     

Long-term survival of human rotavirus in raw and treated river water

This study was aimed at assessing the role of water as a vehicle for rotavirus spread by determining how well these viruses survive in the water environment. A cell culture adapted strain of human rotavirus subgroup 2, grown in MA-104 cells, was used as a model. Virus survival was tested in the following types of water samples, derived from the Ottawa River, at two different times of the year: (i) raw water (RW), (ii) muncipally treated tap water (TW), and (iii) raw water that had been filtered (FW) through a membrane (0.22 micron). The water samples, with approximately 5.0 X 10(4) plaque-forming units (PFU) of the virus, were held at either 4 or 20 degrees C and tested for infectious virus over a period of 64 days. The TW samples had a total and free chlorine content of 0.05 and less than 0.05 mg/L, respectively. The chlorine in these samples was not neutralized before virus contamination. Irrespective of the holding temperature, the virus titre in FW remained essentially unaltered throughout the test period. In TW held at 4 degrees C, there was no significant drop in the virus titre even after 64 days, whereas at 20 degrees C the titre in TW was reduced by about 2 log10 over the same period. Even though the loss of virus infectivity was most rapid in RW held at 20 degrees C, it took about 10 days for a 99.0% reduction in the plaque titre of the virus. These findings, therefore, indicate that rotaviruses can survive for several days in raw and treated river water thus making recreational and potable waters potential vehicles for the transmission of rotavirus infections.     

Chemical disinfection of hepatitis A virus on environmental surfaces

Hepatitis A virus disinfection was assessed on contaminated stainless-steel disks. Ten microliters of fecally suspended hepatitis A virus was deposited on the center of each disk, dried for 20 min, and then covered with 20 microliters of the test product for 1 min. Of the 20 formulations tested, only 2% glutaraldehyde, a quaternary ammonium formulation containing 23% HCl (toilet bowl cleaner), and sodium hypochlorite (greater than 5,000 ppm [greater than 5,000 micrograms/ml] of free chlorine) reduced the virus titer by greater than 99.9%; phenolics, iodine-based products, alcohols, and solutions of acetic, peracetic, citric, and phosphoric acids were unable to do so.     

Chemical disinfection to interrupt transfer of rhinovirus type 14 from environmental surfaces to hands.

Rhinoviruses can survive on environmental surfaces for several hours under ambient conditions. Hands can readily become contaminated after contact with such surfaces, and self-inoculation may lead to infection. Whereas hand washing is crucial in preventing the spread of rhinovirus colds, proper disinfection of environmental surfaces may further reduce rhinovirus transmission. In this study, the capacities of Lysol Disinfectant Spray (0.1% o-phenylphenol and 79% ethanol), a domestic bleach (6% sodium hypochlorite diluted to give 800 ppm of free chlorine), a quaternary ammonium-based product (7.05% quaternary ammonium diluted 1:128 in tap water), and a phenol-based product (14.7% phenol diluted 1:256 in tap water) were compared in interrupting the transfer of rhinovirus type 14 from stainless steel disks to fingerpads of human volunteers upon a 10-s contact at a pressure of 1 kg/cm2. Ten microliters of the virus, suspended in bovine mucin (5 mg/ml), was placed on each disk, and the inoculum was dried under ambient conditions; the input number on each disk ranged from 0.5 x 10(5) to 2.1 x 10(6) PFU. The dried virus was exposed to 20 microliters of the test disinfectant. The Lysol spray was able to reduce virus infectivity by > 99.99% after a contact of either 1 or 10 min, and no detectable virus was transferred to fingerpads from Lysol-treated disks. The bleach (800 ppm of free chlorine) reduced the virus titer by 99.7% after a contact time of 10 min, and again no virus was transferred from the disks treated with it.(ABSTRACT TRUNCATED AT 250 WORDS)     

Rotavirus concentration from cell culture harvests: trypsin treatment followed by hydroextraction.

An 80- to 150-ml amount of calf or simian rotavirus-containing cell culture harvests of MA-104 cells were treated with 50 microgram of trypsin per ml and hydroextracted overnight (4 degrees C) with polyethylene glycol 6,000. The concentrate was resuspended in 8 to 10 ml of tryptose phosphate broth and plaque assayed. Between 85 and 97% of the input virus could be recovered with a concentration of up to 15-fold.     

Viral Pollution of Surface Waters Due to Chlorinated Primary Effluents

The role of chlorinated primary effluents in viral pollution of the Ottawa River (Ontario) was assessed by examining 282 field samples of wastewaters from two different sewage treatment plants over a 2-year period. The talc-Celite technique was used for sample concentration, and BS-C-1 cells were employed for virus detection. Viruses were detected in 80% (75/94) of raw sewage, 72% (68/94) of primary effluent, and 56% (53/94) of chlorinated effluent samples. Both raw sewage and primary effluent samples contained about 100 viral infective units (VIU) per 100 ml. Chlorination produced a 10- to 50-fold reduction in VIU and gave nearly 2.7 VIU/100 ml of chlorinated primary effluent. With a combined daily chlorinated primary effluent output of approximately 3.7 × 10⁸ liters, these two plants were discharging 1.0 × 10¹⁰ VIU per day. Because the river has a mean annual flow of 8.0 × 10¹⁰ liters per day, these two sources alone produced a virus loading of 1.0 VIU/8 liters of the river water. This river also receives at least 9.0 × 10⁷ liters of raw sewage per day and undetermined but substantial amounts of storm waters and agricultural wastes. It is used for recreation and acts as a source of potable water for some 6.0 × 10⁵ people. In view of the potential of water for disease transmission, discharge of such wastes into the water environment needs to be minimized.     

Achieving Balanced Crystallization Kinetics of Donor and Acceptor by Sequential‐Blade Coated Double Bulk Heterojunction Organic Solar Cells

Sequential deposition has great potential to achieve high performance in organic solar cells due to the resulting well‐controlled vertical phase separation. In this work, double bulk heterojunction organic solar cells are fabricated by sequential‐blade cast in ambient conditions. Probed by the in situ grazing incidence X‐ray diffraction and in situ UV–vis absorption measurements, the seq‐blade system exhibits a different tendency from each of the binary films during the film formation process. Due to the extensive aggregation of FOIC, the binary PBDB‐T:FOIC film displays a strong and large phase separation, resulting in low current density (J_sc) and unsatisfactory power conversion efficiency. In the seq‐blade cast system, the bottom layer PBDB‐T:IT‐M produces many crystal nuclei for the top layer PBDB‐T:FOIC, so the PBDB‐T molecules are able to crystallize easily and quickly. Balanced crystallization kinetics between polymer and small molecule and an ideal percolation network in the film are observed. In addition, the balanced crystallization kinetics are favorable toward realizing lower recombination loss through charge transport processes.     

In vivo glucose-6-phosphatase inhibitory,toxicity and antidiabetic potentials of 2-picolylamine thioureas in Swiss albino mice

The 2-picolylamine is a simplest analogue of the alkaloid that has secondary and tertiary nitrogen function in its cyclic structure like that of alkaloids that can be derivatized to a number of biologically active compounds. In connection to our previous work, in the present work, three thiourea derivatives (I = 1,3-bis(2-benzyl-3-phenyl-1-(pyridine-2-yl) propyl) thiourea, II = 1,3-bis (pyridin-2-ylmethyl) thiourea, and III = 1-(2-benzyl-3-phenyl-1-(pyridine-2-yl) propyl)-3-phenylthiourea) were synthesized using 2-picolylamine template which is a readily available synthetic analogue of naturally occurring alkaloid. The biological effect of the synthesized derivatives were monitored on the activity of glucose-6-phosphatase in Swiss albino mice (21-days). The derivatives were also tested for their potential toxicity in a 28-days sub-chronic toxicity studies by assessing their effects on different parameters like hematological, serum biochemistry and liver histology. The therapeutic effect of the safe derivative (I) was examined in streptozotocin-induced diabetic mice as well. The derivatives showed inhibition of the enzyme activity from good to an excellent degree. Compound I had the highest inhibition with 21.42 ± 5.113 mg of the released phosphate as compared to that of the positive control group (84.55 ± 3.213 mg). Only I turned out to be safe for use in animals without exerting any toxic or lethal effects on any of the assessed parameters in the used animal model. Compound I efficiently reversed the effects like hyperglycemia, hyperlipidemia and weight loss in the test animals. Out of these three-tested compounds, I was found safe to be use as therapeutic agent in diabetes complications. However, further toxicological studies in other animal models are needed as well.