Various Conditions Of Storage Research Articles

Stability of GABA levels in CSF under various conditions of storage

Measurement of GABA in human lumbar CSF specimens stored under various conditions showed that the concentrations remained stable in untreated frozen specimens stored at —20°C and at —70°C. In untreated liquid specimens the GABA concentrations approximately doubled during 2 h at room temperature but did not change significantly during 10 min at room temperature or 2 h at 2–4°C. The GABA level was stable at —70°C in deproteinized specimens but doubled during 11 months of storage at —20°C. The level was stable in liquid deproteinized samples for 49 h at room temperature but increased 1.3-fold and 2.0-fold in deproteinized specimens stored for 3 weeks at 2—4°C and room temperature, respectively. Amino acid analyses of homocarnosine standards in 0.1 N HCl revealed a similar increase of GABA during storage at room temperature and at —20°C, suggesting that at least part of the increase seen in CSF specimens might result from breakdown of GABA containing peptides. This instability of GABA level may account for some of the discrepancies among the reports of CSF GABA levels.

A model for the diffusion of vinyl chloride monomer from PVC under various conditions of storage

AbstractThis example of employee safety activity in the vinyl resin industry is illustrative of the efforts put forth by many to achieve acceptable VCM levels in work areas during all conditions of handling. Since use conditions differ greatly at temperatures above Tg temperatures and are nonstatic, it was deemed necessary to develop a model embracing many variables to allow prediction of atmospheric vinyl chloride monomer levels for any combination of the variables.

The fate of folate polyglutamates in meat during storage and processing

The rate of hydrolysis of chicken liver folate polyglutamates, by endogenous liver conjugases, under various conditions of storage, heat, and tissue disruption, were investigated. The procedure used was to allow a radioactive tracer dose of the vitamin to equilibrate into the folate polyglutamyl pool. After various storage periods and treatments the polyglutamyl state of the folate present was examined by analytical techniques based on oxidative degradation of native folate polyglutamates to the corresponding p-aminobenzoylpolyglutamate followed by chromatographic separation on DEAE cellulose anion exchange resin. Identification of folate polyglutamates present was made by simultaneous elution of known p-aminobenzoylpolyglutamate markers. In an intact tissue sample only slight degradation was found after 48 hr at 4 C; complete degradation of folate polyglutamates taking 120 hr. Samples of homogenized tissue show complete degradation to folate monoglutamates and a small amount of diglutamate after 48 hr storage. Superimposed on the above is the consideration that if at any time prior to or during storage the liver is heated to greater than 100 C irreversible inactivation of the endogenous conjugases takes place and the folate polyglutamate pattern is stabilized. It was also demonstrated that during two different heating procedures no extra deconjugation occurred.

Some Storage and Shear History Effects on Polymeric Friction Reduction

The drag reducing properties of two dilute polymer solutions were studied using a simple turbulent pipe flow apparatus under various conditions of storage and mechanical degradation. Aqueous solutions of Polyox WSR-301 (polyethylene oxide) and Separan AP-30 (polyacrylamide) were prepared at 500 ppmw (parts per million by weight) and then diluted into weak concentrations for storage and testing on a day-by-day basis. At concentrations of 10, 25, 50 and 100 ppmw, aged samples showed the same peak effectiveness as freshly prepared ones. However, the aging process reduced the ability to resist mechanical degradation. Anomalies were found in which solutions tend to partially recover from shear degradation under certain conditions, and in other cases tend to improve their friction-reducing efficiency after continuous shearing. Experimental results suggest that entanglement or aggregation of polymer molecules could be one of the important mechanisms involved in friction reduction.

Standardization and stability of immunoglobulin E (IgE)

World Health Organization Reference Standard 68·341 for immunoglobulin E (IgE) was found to contain 2.42 ng. per unit relative to purified myeloma IgE. IgE is relatively stable under various conditions of storage and processing.

The purity stabilisation of sodium o‐iodohippurate (131I)

AbstractTo prevent the autoradiolysis damage in sodium o‐iodohippu‐rate−131 I preparations, various conditions of storage have been tested: storage in isotonic solution frozen at dry ice temperature, and in freeze‐dried state. A preparation which was stable for the guarantee period of about 1 month was obtained by storing it frozen at the temperature about — 70° C. The stability of sodium o‐iodo‐hippurate−131I was compared with that of the similar compound labelled with iodine‐125.

A comparison of pulsatile and nonpulsatile pumping for ex vivo renal perfusion

Dog kidneys were perfused in an ex vivo circuit using a 10-minute interval of autoperfusion (with a slightly damped natural pulse) as a control mode and similar periods of pulsatile and nonpulsatile pumping, randomly alternated, as experimental perfusion modes. In one group of 10 experiments, flow was regulated to the preceding control flow with an occlusive finger pump. In a second group of 10 experiments, pressure was regulated to the preceding control pressure by means of a pressure-controlled servo pump. Pulsation resulted in equal flow at significantly lower pressure in the “adjusted pressure” group. In addition, a degree of autoregulation persisted. Constant pressure appeared superior to constant flow as a means of regulating perfusion, since this provided automatic adjustment to the progressive rise in renal resistance that occurred. Edema did not develop during the five-hour periods of perfusion, indicating the basic soundness of both regulating methods. The most logical explanation for the superiority of pulsatile flow is to be found in the viscoelastic properties of the renal vessels which impart a capacitive flow effect that is augmented by pulsatility. The higher frequency, “natural,” pulse was superior to both experimental pump pulses indicating the desirability of further defining the characteristics of an optimal pulse under various conditions of storage including hypothermia.

Aldrin epoxidase activity of rat liver and rat liver microsomes under various conditions of storage

The stability of rat hepatic microsomal mixed function oxidation systems stored under various conditions was assessed by a measurement of aldrin epoxidase, NADPH cytochrome c reductase, NADPH neotetrazolium reductase activities and cytochrome P-450 levels. Male rat livers stored at − 20° for 30 days showed little loss of the two NADPH-dependent microsomal reductase activities and cytochrome P-450. Microsomal suspensions from these livers showed higher protein content, increased aldrin epoxidase activity, decreased endogenous as well as NADPH-dependent lipid peroxidation and higher stability during storage at 4°. The microsomal epoxidase systems of liver were less stable when stored as microsomal pellets than as whole liver at either −10° or−20°. Enzymes in microsomal suspensions prepared from fresh liver were unstable at 4°, but retained full activity if the suspensions contained 10 −2 M KCN or were prepared from prefrozen livers. These results indicate that freezing of the liver causes a structural change in microsomes resulting in an increase in epoxidase activity.

The stability of endogenous and exogenous corticotrophin in rat plasma as established by a bioassay in intact rats.

SUMMARY Corticotrophin (ACTH) activity in rat plasma, both endogenous (adrenalectomized rat plasma) and exogenous (International Working Standard, 1962), has been assayed in dexamethasone-treated rats and the stability studied under various conditions of storage. Exogenous ACTH added to rat plasma and assayed immediately had only 76% of the activity of the same ACTH dissolved in gelatine acid saline medium. This difference is ascribed to the effects of the medium and not to inactivation. When allowance was made for the effects of the medium on potency, added ACTH showed a similar stability on incubation or storage to endogenous ACTH. For endogenous ACTH the following loss of activity was found in vitro: after 45 min. at 37°, 64%; after 1 day at room temperature, more than 85%; after 1 day at 3°, 58%. No loss of potency was detected on storage at −17° for 18 months. It is concluded that plasma can be frozen, stored at low temperature, and thawed without significant loss of corticotrophic potency provided that the blood is chilled as soon as drawn and the subsequent operations performed expeditiously.

TOXICITY OF CELL CULTURE MEDIUM DUE TO FILTRATION THROUGH ASBESTOS PADS.

DURING investigations of tissue culture cells under various conditions of storage, it was observed that the viability of a single cell batch varied when tested with different batches of the same medium. This variation was found to be related to the order in which the medium batch was collected during filtration using standard asbestos pads.

Serological "Shelf-Life" of Serum Proteins under Various Conditions of Storage

Serological "Shelf-Life" of Serum Proteins under Various Conditions of Storage

GAL virus: Its growth cycle in tissue culture and some of its properties

The GAL virus growth cycle has been determined by plaque assay and correlated with electron microscope observations of infected cells. The virus was found to have a long latent period and growth cycle, to be produced only within the cell nucleus, and to accumulate there. It also was found to be polyhedral in shape and ether stable and to resemble adenovirus in its intranuclear site of development, its morphology, and its ether stability. Data concerning its stability under various conditions of storage are included.

Placental oxygen consumption in vitro: I. Baseline studies

Barcroft-Warburg respirometric observations of fresh in vitro placental tissue have been reported as part of a correlative study of the effects of various clinical features upon placental metabolism and their relationship to fetal development and survival.Data are presented to illustrate the rates of decay of placental activity under various conditions of storage, indicating the urgent need to study the material in the freshest possible state. Similarly, degradation occurs so rapidly during manometric studies that consecutive observations for the purpose of determining the effects of adding substrates are interdicted.The reduction of the oxygen concentration of the gas phase produces a corresponding, although nonlinear, reduction in oxygen uptake.Normal term placentas consume 2.02 ± 0.03 μl of oxygen per milligram of dry weight per hour. A linear decline is seen from early pregnancy to term.Numerous clinical factors are correlated with placental oxygen consumption, but, except in rare instances, the data are not sufficiently numerous to allow for statistical verification of observed trends.

Design and Analysis of Two Phase Experiments

It sometimes happens in experimental work that the effects of different treatments cannot be measured directly and a further stage of testing is required in order to evaluate them. Examples of this type of situation are studies of the effect of conditions of growth of parent material on resistance to disease or productivity of progeny; the survival of nodule bacteria under various conditions of storage and appraised by inoculating appropriate legume seedlings; and the effect of various treatments on virus multiplication in leaf tissue, the concentration of virus being ascertained by lesion counts on indicator plants.

BACTERIOLOGICAL STUDIES OF A FARM BULK MILK HANDLING SYSTEM

Studies were conducted on the bacteriology of a farm bulk milk handling system. The sanitary condition of two bulk cooling tanks was tested by the swab-contact method. Milk samples were taken under various conditions of storage to determine the time of agitation required to permit representative sampling for bacteriological testing. The milk was sampled for bacteriological analysis after one and two days of storage in the bulk tanks to determine the effect of every-other-day pickup. The milk was sampled at the farm and at the dairy plant to determine the effect of tanker transportation.Results from these studies indicated that the flat open surfaces of the cooling tanks were generally cleaned in a satisfactory manner but that valves required special care in cleansing. Ninety seconds of agitation permitted representative sampling for bacteriological tests under all test conditions. Neither every-other-day pickup nor tanker transport adversely affected milk quality in the system being studied.

SOME ASPECTS OF RECENT HOP RESEARCH

Storage and brewing trials on several varieties of hops show, in general, that the relative stabilities of beers brewed at a hop rate of one pound per barrel from a given series of hops are directly related, during the first year of storage, to the respective humulone contents of the new hops at the time when they were received. Certain aspects of the results so far obtained are considered in the light of recent Belgian work on the antiseptic constituents of hops. At the ph of wort, humulone boiling product has a bacteriostatic potency equal to 43 per cent, of that of humulone; in beer, no significant difference could be detected between the bacteriostatic potency of humulone and that of its boiling product. The effects of various conditions of storage on the stability of hop resin fractions, and of crystalline humulone and lupulone, are described. The stabilities of humulone and of the crude, α-fraction are affected by the presence of the β-fraction, and by the nature of the atmosphere in which the materials are stored. The bacteriostatic properties of some of the products obtained have been investigated.

The Shrinkage of Acetate-Base Motion Picture Films

A simple direct-reading film-shrinkage gauge has been constructed with which shrinkage readings may be made in a few seconds. The accuracy of the instrument is such that the maximum variation in a series of readings made upon a particular film will not be more than 0.02 per cent of the predetermined length measured. Readings have been taken systematically with this instrument over a period of five months to determine the shrinkage behavior of acetate-base films under various conditions of storage and use. — The results indicate that the safety-base film made by each of the three American manufacturers has a characteristic value of shrinkage that is ordinarily reached within a few days after processing. Subsequent shrinkage is slow but continuous over a long period of time. The ultimate shrinkage is of the order of 1.25 per cent except in the case of films that have been projected many times on projectors using high-wattage lamps. The bearing of this shrinkage information upon equipment design is discussed briefly.

The effect of various conditions of storage on the potency of tincture of digitalis

The effect of various conditions of storage on the potency of tincture of digitalis