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Biomedical subjects

M Winick

Publications and source records attributed to M Winick.

At least 55 records · Page 3Linked to original sources
PubMed1980

Effects of administration of N-acetylneuraminic acid (NANA) on brain NANA content and behavior.

Rat pups were malnourished during the first 3 weeks after birth. Experimental rats were injected intraperitoneally with 1 mg N-acetylneuraminic acid (NANA) per 50 g body weight daily from 14 to 21 days postnatally. Control animals were similarly injected with 1 mg glucose per 50 g body weight. At 21 days of age, the rats were tested in an open field and their brains analyzed for protein, DNA, ganglioside NANA and glycoprotein NANA. The administration of NANA was associated with an increase in cerebral and cerebellar ganglioside and glycoprotein NANA concentrations. However, it had no effects on brain weight, cell size and number. There was also a reduction in the expected behavioral abnormalities secondary to malnutrition. At 21 days of age, similarly treated littermates of the experimental animals were weaned to a stock diet and tested in a Y maze at 6 months of age. Rats treated with NANA learned the maze quicker than controls and the previously noted changes in brain biochemistry were found to have persisted. Intraperitoneal injection of [14C]NANA into malnourished rats during the same period showed that it was readily incorporated into brain glycoproteins and gangliosides. The possibility that the brain concentration of NANA has an effect on behavior is discussed.

Animals↗
PubMed1980

Effects of environmental stimulation on brain N-acetylneuraminic acid content and behavior.

A study was conducted in which the nutritional and early stimulation conditions of rat pups were manipulated during the first 3 weeks of life. Early stimulation reduced the change in open-field behavior caused by malnutrition at 21 days postnatally. The cerebrum and cerebellum were analyzed for ganglioside and glycoprotein N-acetylneuraminic acid (NANA), DNA and protein content. The improved behavioral performance was associated with a significantly higher ganglioside and glycoprotein NANA content in both brain areas analyzed. The remaining rats from each litter were weaned onto a standard laboratory stock diet at 21 days of age and housed individually until age 6 months. At this time, their performance in a Y maze was tested. Once again early stimulation was associated with an improved ability to learn the maze. The biochemical changes persisted into adulthood in the stimulated groups with the exception that the difference in cerebellar ganglioside content had disappeared by this time. The results are discussed with respect to the possible role of NANA in behavior.

Aging↗
PubMed1979

Behavioral and physiological effects of early handling and early malnutrition in rats.

This experiment employed a 2 x 2 design in which the nutritional and early stimulation conditions of rat pups were manipulated during the 1st 3 weeks of postnatal life. Animals were observed in various open field activities at 22, 23, 29, 36, and 50 days of age, and killed at 55 days of age for neurochemical analysis. Early handling decreased the behavioral differences due to malnutrition and resulted in fewer, but larger cells in rat forebrain for both well-nourished and malnourished groups.

Adrenal Glands↗
PubMed1978

The effects of folic acid supplementation during pregnancy in the rat.

1. Twenty-four Sprague-Dawley female rats were randomly assigned to three groups (groups A, B, C). Group A was given a folic acid-free diet and groups B and C received 0.0018 g folic acid/kg diet. Rats in group C were also given a supplement of 1 mg folic acid/d by intraperitoneal injection. 2. After 14 d of feeding the rats were mated. The diets were continued throughout gestation. On day 21, of gestation the dams were killed and their livers and products of conception assayed for RNA, DNA, protein and tetrahydrofolate dehydrogenase (5,6,7,8-tetrahydrofolate dehydrogenase; EC 1.5.1.3) activity. 3. The foetuses, placentas and livers from supplemented rats (group C) were significantly larger than those from groups A and B and had a higher content of RNA, DNA and protein. Those tissues from group A dams were smaller than those from the other groups and had a correspondingly reduced nucleic acid and protein content. 4. The activity of tetrahydrofolate dehydrogenase, the first and rate-limiting enzyme in the metabolism of folate, was increased in the folate supplemented rats (group C) and reduced in the rats given a folic acid-free diet (group A). These changes in enzyme activity could explain the differences in nucleic acid biosynthesis and growth shown by the different groups.

Animals↗
PubMed1978

Effect of malnutrition and rehabilitation on the metabolism of polyamines in rat liver.

In adult male rats the activity of ornithine decarboxylase (ODC) and S-adenosylmethionine decarboxylase (SAMD) and the concentration of putrescine and spermidine increased markedly 3 to 4 weeks after feeding the animals a 6% casein diet. Incorporation of [14C]orotic acid into nuclear RNA also increased during this period of time. In contrast, spermine concentration remained unchanged. During the fifth week of protein restriction enzyme activities, putrescine and spermidine concentrations and orotic acid incorporation returned to control levels. After the restricted rats were put on a control diet there was a rapid increase above control levels in ODC activity and a proportionally smaller increase in SAMD activity. Putrescine and spermidine concentration also increase above control levels. Both enzyme activities and polyamine concentrations were within normal levels 96 hours after refeeding. Spermine values were unmodified by refeeding. After a transient rise 12 hours after refeeding, incorporation of labeled orotic acid into RNA decreased significantly for the rest of the experiment.

Adenosylmethionine Decarboxylase↗
PubMed1978

Studies on ribosomal RNA synthesis in vivo in rat liver during short-term protein malnutrition.

To better understand the increased incorporation of [14C] orotate into rRNA, as detailed study of liver rRNA synthesis was performed on young rats fed a 6% casein diet for 1 week. From 10 to 180 minutes after i.v. injection of [14C] orotate, nucleolar RNA specific activity of malnourished rats was 1.6 times higher than controls. Polyacrylamide gel electrophoresis revealed that 45S pre-rRNA from malnourished rats was synthesized more rapidly than controls. Specific activities of other nucleolar RNA species was increased but the time of appearance of labeled peaks did not change. The cellular cytoplasmic rRNA pool was reduced to 70% of controls, the time of appearance of labeled rRNA in the cytoplasm was the same, but cytoplasmic rRNA specific activity was 2.1 times greater than controls. Absorbance profiles and radioactivity patterns of nucleoplasmic RNA were similar in the two groups of rats. Nucleoplasmic radioactivity patterns were complex and heterodispersed, and the amount of radioactivity was greatest in RNA from malnourished rat liver. Our data indicate that short-term dietary protein restriction leads to cellular events which increase the synthesis of nuclear RNA. Nucleolar RNA is processed and transported to the cytoplasm in a manner similar to controls.

Animals↗
PubMed1977

Effects of malnutrition on some aspects of RNA metabolism in the maternal liver and fetal tissues at different stages of pregnancy in the rat.

A comparison was made between rats fed diets containing either 5% casein or 25% casein, both being supplemented with DL-methionine, from the first day of pregnancy. Livers of dams killed on days 7, 14, and 21 and whole fetuses on days 12, 14, and 21 were weighed, analyzed for protein, RNA and DNA content and assayed for ornithine decarboxylase (ODC) and S-adenosyl-L-methionine decarboxylase (SAMD). Free and total alkaline ribonuclease activity were also measured in the maternal livers. Malnutrition reduced the characteristic increase in content of DNA, RNA and protein in the maternal liver and fetus. In control rats total hepatic RNase activity increased and free RNase activity decreased during late pregnancy. In the deprived group, total activity decreased and free activity increased during late pregnancy. Liver and fetal ODC and SAMD activities were reduced by undernutrition. These studies show that malnutrition reduced both growth and the accretion of RNA in livers and fetuses of rat dams. These changes coincide with a reduced activity of polyamine synthesizing enzymes suggesting that there is a functional relationship between polyamines and RNA. High hepatic free RNase activity in malnourished dams may help to limit any build up in RNA content.

Adenosylmethionine Decarboxylase↗
PubMed1975

Activity of alkaline RNase in placentas of malnourished women.

Pregnancies were compared in 18 Ecuadorian women of low socioeconomic status and 11 of high socioeconomic status. Objective evidence of malnutrition was demonstrable in virtually all of the women from the low socioeconomic group and in none from the high socioeconomic group. Birth weight and placental weight were significantly lower in the malnourished group. Nucleic acid and protein content of placentas were slightly lower and activity of alkaline ribonuclease was markedly elevated. The data reinforce animal studies and demonstrate for the first time in human subjects that alkaline RNase activity is increased in placentas from malnourished women. We suggest that activity of this enzyme in placenta may prove to be a useful marker of maternal and fetal nutritional status.

Ecuador↗