Alcohol dehydrogenase and retinol dehydrogenase in bovine retinal pigment epithelium

Wastewater aerosols produced during flushing toilets, WWTPs, and irrigation with reclaimed municipal wastewater as indirect exposure to SARS-CoV-2

The detection of SARS-CoV-2 RNA in raw and treated wastewater can open up a fresh perspective to waterborne and aerosolized wastewater as a new transmission route of SARS-CoV-2 RNA during the current pandemic. The aim of this paper is to discuss the potential transmission of SARS-CoV-2 RNA from wastewater aerosols formed during toilet flushing, plumbing failure, wastewater treatment plants, and municipal wastewater reuse for irrigation. Moreover, how these aerosols might increase the risk of exposure to this novel coronavirus (SARS-CoV-2 RNA). This article supplies a review of the literature on the presence of SARS-CoV-2 RNA in untreated wastewater, as well as the fate and stability of SARS-CoV-2 RNA in wastewater. We also reviewed the existing literatures on generation and transmission of aerosolized wastewater through flush a toilet, house's plumbing networks, WWTPs, wastewater reuse for irrigation of agricultural areas. Finally, the article briefly studies the potential risk of infection with exposure to the fecal bioaerosols of SARS-CoV-2 RNA for the people who might be exposed through flushing toilets or faulty building plumbing systems, operators/workers in wastewater treatment plants, and workers of fields irrigated with treated wastewater - based on current knowledge. Although this review highlights the indirect transmission of SARS-CoV-2 RNA through wastewater aerosols, no research has yet clearly demonstrated the role of aerosolized wastewater in disease transmission regarding the continuation of this pandemic. Therefore, there is a need for additional studies on wastewater aerosols in transmission of COVID-19.

Simultaneous analysis of esterase and transferase activities in cytosol proteins from the bovine retina by using microscale non-denaturing two-dimensional electrophoresis

Esterase and transferase activities were analyzed simultaneously after cytosol proteins in the bovine retina were separated by microscale non-denaturing two-dimensional electrophoresis (2-DE). Esterase activity was specifically inhibited by an esterase inhibitor, 9-amino-1,2,3,4-tetra hydroacridine (tacrine), and transferase activity was specifically inhibited by a glutathione S-transferase (GST) inhibitor, 2-phenyl-1,2-benziso selenazol-3(2H)-one (ebselen). Both esterase and transferase were precipitated when ammonium sulfate was added to the cytosol up to 50% saturation (50% AS fraction), and were detected in the 50% AS fraction by using the 2-DE. After the cytosol proteins in the 50% AS fraction were separated by using non-denaturing 2-DE, polypeptides of the separated proteins were identified by peptide mass fingerprinting and post-source decay analysis by using MALDI-MS, or by immunoreactivity by using a specific antibody. The spots of esterase and transferase activities in the 2-DE pattern were identified as phosphodiesterase and GST, respectively. This simultaneous analysis of enzyme activities can be applied to screen-specific or non-specific medicines which affect enzyme activities.

All-trans to 11-cis retinol isomerization in nuclear membrane fraction from bovine retinal pigment epithelium

Isomerization of all-trans to 11-cis retinol has been studied in a membrane preparation from the nuclear fraction of bovine retinal pigment epithelium. When the nuclear membrane preparation deprived of endogenous retinoids is incubated with 4.5 microM all-trans-retinol, the mean value calculated for the isomerase activity is 1.32 nmol 11-cis retinol formed hr-1 mg protein-1. Simultaneous formation of all-trans and 11-cis retinyl esters is also observed in the nuclear preparation. When assayed under the same experimental condition, RPE 150,000 g post-nuclear sediment shows about 70% of the isomerase activity found in the nuclear membrane fraction. Treatment of the nuclear membrane fraction with 0.5% (w/v) CHAPS produces a 200,000-g supernatant retaining 80% of the total isomerase activity and leads to a modest purification of the enzyme activity. Apparent values for Km and Vmax of the solubilized enzyme are 1.6 microM and 2.5 nmol 11-cis retinol formed h-1 mg protein-1, respectively. Bovine serum albumin and beta-lactoglobulin effectively stimulate the isomerization reaction. The mechanism underlying this activating effect remains unclarified at present. Some hypotheses are discussed.

NAD+-dependent retinol dehydrogenase in liver microsomes

A microsomal NAD+-dependent retinol dehydrogenase is being described with optimal activity at physiological pH. The enzyme was present in liver microsomes of rats and also in a strain of deermice which lacks the cytosolic retinol dehydrogenase. Unlike the latter enzyme, the microsomal retinol dehydrogenase was not inhibited by either ethanol or 4-methylpyrazole; its activity was insensitive to CO and not oxygen dependent, in contradistinction with that of the microsomal cytochrome P-450 and NADPH-dependent retinol oxidase. Chronic ethanol consumption resulted in an increased activity of the microsomal retinol dehydrogenase which may contribute to hepatic retinol depletion, especially in view of the insensitivity of the enzyme to ethanol inhibition.

An antioxidative role of ocular screening pigments

The action of ocular screening pigments of vertebrates (melanins) as well as those of invertebrates (ommochromes) on lipid peroxidation has been studied. Lipid peroxidation has been induced by one of the following systems: Fe2+ + ascorbic acid; Fe2+ + NADPH + liver microsomes; xanthine + xanthine oxidase; u.v. illumination; intense visible light, high concentration of O2. Measurements of the lipid peroxidation rate, as estimated from the accumulation of malonic dialdehyde, showed a sharp decrease of the lipid peroxidation rate in the presence of either melanosomes or ommochromes. Synthetic DOPA melanin was also found to exert a strong inhibiting effect on lipid peroxidation. A comparative study of lipid peroxidation in retinal pigment epithelium (RPE) of pigmented and albino rabbits demonstrated that the latter tissue is more sensitive to the effect of the above mentioned prooxidant systems. Apparently this finding is related to the presence of melanin-containing granules in the pigmented tissue rather than to differences in efficiency of other endogenous antioxidant systems. The activities of superoxide dismutase and glutathione peroxidase are practically equal in the RPE of pigmented and albino rabbits whereas the alpha-tocopherol content is higher in albinos. Possible mechanisms of inhibition of lipid peroxidation by melanosomes and ommochromes are discussed. It is proposed that their antioxidant function is one of the most important physiological features of melanins (vertebrate eye) and ommochromes (invertebrate eye).

Normal electroretinogram and no toxicity signs after chronic and acute administration of the alcohol dehydrogenase inhibitor 4-methylpyrazole to the cynomolgus monkey (Macaca fascicularis)--a possible new treatment of methanol poisoning

High doses of 4-methylpyrazole (4-MP) could be administered to monkeys in long- and short-term experiments without yielding any general toxicity or any toxic influence on the retinal photoreceptors, the conduction of impulses through the retina or on the activity in the inner nuclear layer detectable by recording the electroretinogram (ERG). Both series included a low dose (20 mg/kg) and a high dose level (100 mg/kg), the former being a tentative therapeutic dose. In the first series the substance was administered for 6 weeks and the toxicity regarding clinical signs, hematology and blood chemistry, and gross and microscopic pathology evaluated. Furthermore ophthalmoscopy with assessment of the fundus structures and recordings of the ERG were performed. The second series was mainly concerned with revealing of any direct effect of 4-MP on the ERG. Because of the low toxicity of 4-MP and its powerful inhibitory capacity on alcohol dehydrogenase, the substance should prove a potential tool in clinical alcohol research and an effective antidote in clinical situations where inhibition of alcohol dehydrogenase (ADH) is the key to a successful outcome of, for example, methanol and ethylene glycol poisoning.

Isolation procedure for bovine retinal rod outer segments

An isolation procedure to obtain rod outer segments from cattle retinas is reported. Centrifugation of homogenates in discontinuous and continuous sucrose density gradients yields purified photoreceptor cell outer segments. Assay of the final preparation for rhodopsin content gives a ratio of 2.4 for DO280nm/DO498nm.