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M Rothstein

Publications and source records attributed to M Rothstein.

At least 55 records · Page 3Linked to original sources
PubMed1979

The formation of altered enzymes in aging animals.

Evidence is accumulating which supports the idea that the alteration of enzymes is due to post-synthetic modifications rather than to sequence changes. Although unequivocal proof is still lacking, the idea that the changes in old enzymes are due to a subtle denaturation rather than to covalent changes is strengthened by recent work. That altered enzymes may result from a slowed protein turnover in old organisms appears to be a viable hypothesis.

Aging↗
PubMed1979

Accelerating effect of ascorbic acid on N-nitrosamine formation and nitrosation by oxyhyponitrite.

The reaction of nitrite ion with ascorbic acid and its effect on the rate of nitrosation of secondary amines have been investigated by differential pulse polarography in aqueous acidic solution. Ascorbic acid shows nonuniform behavior: it accelerates the nitrosation of N-methylaniline between pH 1.00 and 1.95, allows the nitrosation of diphenylamine and iminodiacetonitrile, but inhibits the nitrosation of secondary amines, such as dimethylamine, diethylamine, proline, hydroxyproline, N-methylaminoacetonitrile, N-methylaminopropionitrile, and sarcosine. The nitrosating agent generated by the reaction between ascorbic acid and nitrite ion appears to be oxyhyponitrite ion (N2O3-2).

Ascorbic Acid↗
PubMed1979

Duration of hepatitis B surface antigenemia (HBs Ag) in hemodialysis patients.

Follow-up studies were done on 231 hemodialysis patients during a period of from one to 48 months to determine the natural history of hepatitis B surface antigenemia (HBs Ag). Of those studied, 113 (49%) exhibited HBs Ag. The probability of remaining HBs Ag positive over the mean follow-up period of 14.4 months was 62%. All of the 38 patients whose HBs Ag reverted to negative did so within ten months. Those patients whose HBs Ag reverted to negative had SGOT levels that were less frequently elevated than the patients with persistent antigenemia. Of hemodialysis patients with HBs Ag, 60% showed e antigen (HBe Ag).

Adult↗
PubMed1978

Altered enzymes in the free-living nematode, Turbatrix aceti, aged in the absence of fluorodeoxyuridine.

Aging of the free-living nematode, Turbatrix aceti, has been accomplished by a procedure based upon screening of the cultures every 3--4 days to remove newborn organisms. In this system, the enzymes, isocitrate lyase, phosphoglycerate kinase and enolase all show reduced specific activities with age in crude homogenates. More critically, pure enolase shows a reduced specific activity when isolated from old compared with young organisms (958 units/mg vs. 1340 units/mg, respectively). Immunotitration experiments confirm these results. Enolase from old T. aceti requires more antiserum per unit of enzyme activity than does enolase from young organisms. This relationship holds true for both crude homogenates and pure enzyme. The above results closely parallel previous results obtained using fluorodeoxyuridine to prevent reproduction of T. aceti during aging of the organisms. Therefore, use of fluorodeoxyuridine in the aging of nematodes is perfectly safe, at least with respect to results obtained with altered enzymes.

Aging↗
PubMed1978

Serological evidence for the alteration of enolase during aging.

Pure enolase isolated from young and old Turbatrix aceti has been compared using immunologic techniques. Antiserum prepared to "young" and "old" enolase, respectively, will completely precipitate either enzyme. However, antiserum prepared to "young" enolase reacts more efficiency with "young" than with "old" than with "old" enzyme and vice versa. A third form of enolase (inactive enolase) is found in homogenates of old organisms. This material yields a pattern of identity with "young" enolase and partial identity with "old" enolase. It also gives rise to specific antibodies which do not react with "young" or "old" enolase. The material appears to accumulate with age. The results indicate a close structural relationship between "young", "old" and inactive enolase.

Aging↗
PubMed1978

Nutritional factors and conditions for the axenic culture of free-living nematodes.

1. Soy-peptone has been fractionated to yield a series of increasingly purified components which sharply increase the populations of Caenorhabditis briggsae and Caenorhabditis elegans when added to the basal medium. The nutritionally active material appears to be a small polypeptide. 2. C. briggsae and C. elegans routinely reach populations of 150,000/ml or greater in 9 days in still culture, starting from an inoculum of only 500 organisms per ml. C. elegans is particularly sensitive to the depth of the medium. However, large populations can be achieved in deep cultures if continuous shaking is carried out. 3. Panagrellus silusiae shows improved populations if the basal medium is supplemented with the nutritional factor from soy-peptone. However, 0.5% acetic acid or 1% ethanol added to the medium serves equally well. There is no additive effect of ethanol and the factor.

Animals↗
PubMed1976

Phosphoglycerate kinase from young and old Turbatrix aceti.

Phosphoglycerate kinase (ATP:3-phospho-D-glycerate-1-phosphotransferase, EC 2.7.2.3) from young and old Turbatrix aceti has been purified to homogeneity. The "old" enzyme exhibits a marked reduction in specific activity both in crude homogenates and in pure form when compared to preparations from young nematodes. The specific activities for pure "young" and "old" enzymes are 650-750 and 300-400 units/mg, respectively. All other properties of "young" and "old" enzymes were nearly identical, including molecular weight (43 000), Km, behavior on columns, thermal stability and mobility during gel electrophoresis at three pH values. The results are discussed in terms of the possible mechanism of formation of "altered" enzymes. In addition, certain properteis of the nematode phosphoglycerate kinase are compared with those of the enzyme from yeast and rabbit muscle.

Aging↗
PubMed1975

Age-related changes in isocitrate lyase from the free living nematode, Turbatrix aceti.

Isocitrate lyase from both young and old free living nematodes (Turbatrix aceti) has been purified and compared. The "old" enzyme consists of the same five isozymes as the "young" preparation, but with quantitative differences. The enzyme shows an age-related decline in specific activity. Use of antibodies has confirmed the accumulation of cross-reacting material in old organisms as found by Gershon and Gershon ((1970) Nature 227, 1214), using crude homogenates. Km, molecular weight, subunit size, and behavior toward the inhibitors oxalate, malonate, and tartronate all appear unchanged. Although the enzyme isolated from old organisms has a sharply reduced specific activity, it binds as well to an affinity column as does "young" enzyme. It is tentatively concluded that the loss of specific activity in the "old" enzyme is due to the presence of partially active molecules, rather than to a mixture of active and inactive molecules.

Aging↗