Gluconeogenesis from lactate in the small intestinal mucosa of suckling rats

Glucose formation from uniformly labeled 14C-lactate was studied in the small intestinal mucosa of rats and rabbits. It was found to occur in infant but not in adult (weaned) animals and to be increased by the presence of dibutyryl cyclic AMP or tetradecyl glycidic acid. Similarly the formation of glyceride glycerol was enhanced by tetradecyl glycidic acid but not by glucagon or cyclic AMP. The glycogen content of the intestinal mucosa was always low, but increased significantly at the time of weaning. It is suggested that gluconeogenesis occurs in the small intestinal mucosa of infant rodents to supply glucose to the muscular part of the small intestine.

Multiphasic MR imaging: a new method for direct imaging of pulsatile CSF flow

A new technique is described that allows for the creation of pure pulsatile flow magnetic resonance (MR) images in a single acquisition. Five to 16 electrocardiographically gated images spanning the entire cardiac cycle are obtained with use of a gradient-echo pulse sequence. The section can be varied from 4 mm thick to full thickness projection. Taken singly, each image provides direct assessment of flow direction and velocity. Subtraction of image pairs eliminates signal detected from stationary protons, producing images of pulsatile flow. In this study the technique was used to image the flow of cerebrospinal fluid (CSF) in healthy subjects and in one patient with syringohydromyelia. The data suggest that multiphasic MR imaging provides a powerful means for the noninvasive assessment of CSF pulsatile flow dynamics and may have potential clinical application for the investigation of a variety of abnormalities such as normal pressure hydrocephalus, syrinx, and spinal block.

Spontaneous and 3-aminobenzamide-induced sister-chromatid exchange frequencies estimated by ring chromosome analysis

Ring chromosomes offer an opportunity to measure sister-chromatid exchange (SCE) frequencies without the use of an agent to differentiate sister chromatids: SCE frequencies can be determined from the number of dicentric rings formed in cells from a cell line carrying a monocentric ring chromosome. Ash is a pseudotetraploid Chinese hamster ovary cell line in which approximately 40% of metaphase cells have a large ring chromosome. We have used this cell line to investigate the spontaneous rate of SCE by determining the rate of dicentric ring formation and have compared this with the rate of loss of the ring chromosomes over time. In the absence of both [3H]thymidine and bromodeoxyuridine, the spontaneous rate of SCE in Ash cells was 0.12 SCEs/ring/cell cycle; this rate was increased by bromodeoxyuridine, by the polyfunctional alkylating agent mitomycin C, and by the poly(ADP-ribose) polymerase inhibitor 3-aminobenzamide. This indicates that spontaneous SCE occurs in this line and that not all 3-amino-benzamide-induced SCEs are dependent upon incorporated bromodeoxyuridine. Ring chromosomes were not lost over time as rapidly as predicted by the SCE frequencies observed. Non-disjunction of the dicentric ring, or anaphase bridge breakage followed by reunion to form one or two monocentric rings, are the most likely explanations for this discrepancy.

Chromosomal changes without DNA overproduction in hydroxyurea-treated mammalian cells: implications for gene amplification

It has been reported that a 6-h incubation of early S-phase Chinese hamster cells with hydroxyurea promotes DNA overproduction, i.e., replication of DNA a second time within a single cell cycle, and that this could be the basis for gene amplification in drug-treated mammalian cells. When we incubated methotrexate-resistant Chinese hamster cells that were approximately 2 h into the S phase with hydroxyurea for 6 h, DNA that had been replicated before the incubation with hydroxyurea (early S-phase DNA) was replicated again within 11 h after the hydroxyurea treatment. However, incubation with colchicine or Colcemid after hydroxyurea treatment virtually abolished this overreplication, as well as that of the amplified dihydrofolate reductase genes in these cells, indicating that the second replication had occurred in a second cell cycle. Cells collected in the first mitosis after incubation with hydroxyurea never contained overreplicated DNA but did contain abundant chromosome aberrations. Early S-phase DNA replicated again on schedule during the first few hours after mitosis. Asymmetric segregation of chromosome fragments or unequal sister chromatid exchange may be the actual basis for gene amplification in drug-treated mammalian cells.

Effect of age and diet on cyclic nucleotide concentrations in the intestinal mucosa of developing rats

Mucosa isolated from the proximal third of the small intestine of infant rats had much lower cyclic nucleotide concentrations (expressed both per unit wet weight and per unit DNA content) than those determined in the intestinal wall. The steady-state concentrations of both cyclic AMP and cyclic GMP in jejunum showed dramatic increases during the first 5 d post partum. Another increase in cyclic nucleotide concentrations was observed in the isolated mucosa between d 15 and 21. Starvation for 24 h always resulted in lower intestinal cyclic nucleotide concentrations than those of the fed littermates. This effect was more pronounced in younger animals and more evident for cyclic AMP values. Three-week-old rats fed a high carbohydrate diet for 24-48 h exhibited more pronounced elevations in the concentrations of cyclic nucleotides from the jejunal mucosa than did rats fed a high fat diet.

A double-blind placebo-controlled trial of progesterone vaginal suppositories in the treatment of premenstrual syndrome

Rigorous criteria were used to select women with severe premenstrual syndrome for inclusion in an 8-month double-blind placebo-controlled clinical trial of progesterone vaginal suppositories. Following a control month without treatment, progesterone (200 mg in polyethylene glycol base) or placebo was self administered twice daily by vaginal suppository for a minimum of 12 days before the onset of menstruation for 3 months. Crossover to the opposite medication for a further 3 months was followed by a final control cycle without treatment in month 8. Physician contact was minimized throughout the study to avoid any possible positive effects of psychological support which may have confounded past investigations. Detailed self-report questionnaires were completed every 3 days for the duration of the study. Although the attrition rate was high, 20 women completed the trial and their records are analyzed here. The results of this trial indicate that the response to vaginal progesterone in these dosages is, at best, marginal and not significantly different from response with placebo use.

2-14C-mevalonate oxidation during rat development

In vivo oxidation of 2-14C-mevalonate is very low in 1- to 3-day-old rats and then rises to adult levels. Kidney slices oxidize mevalonate at an equal rate during development. However, at the time of weaning the rate is transiently increased in male rats only.

Effect of hypothyroidism during gestation and in the suckling period on cholesterol and carnitine metabolism in the rat

Propylthiouracil (PTU; 0.05%) was added to the drinking water of rats of various ages and their response was monitored. PTU resulted in reduced body weights in both fetuses and young rats 0-30 days old. Plasma cholesterol levels were elevated and the activities of hepatic 3-hydroxy-3-methyl-glutaryl CoA reductase (HMGCoAR) and 7-alpha-hydroxylase were decreased if PTU was present in the water up to the time of death. However, if no PTU was present for some time before death, this effect was no longer observed. Plasma total carnitine levels were always suppressed by PTU and appeared the most sensitive indicator of PTU action. Intestinal acylcholesterol acyltransferase (ACAT) activity was elevated nearly 5-fold, while intestinal HMGCoAR activity was only slightly and occasionally depressed.

Lipid synthesis in various organs of the rat during postnatal development

The incorporation of 3H2O into the lipids of brown and white adipose tissue (BAT and WAT), skin, liver, heart, kidney, brain and lungs was studied 1 h after injection in rats aged 1, 13 and 22 days. In the younger age group, triglyceride synthesis was considerably higher in BAT than in any other tissue, while in the 22-day-old rats, this is no longer the case. Cholesterol synthesis in the oldest age group was highest in liver. In the younger animals, there was little difference between tissues in the low rate of cholesterol synthesis except in the brain where the rates of all lipid syntheses were highest on day 13. The surprisingly high rate of triglyceride synthesis in BAT of infant rats is partly due to the high rate of synthesis of the glycerol moiety. Nevertheless, on hydrolysis, the rate of fatty acid synthesis was still highest in these animals.

Nutrition and metabolic development

Perinatal changes in metabolic processes owing to a change from a high carbohydrate to a high fat (milk) diet at birth are described. It is pointed out that early changes in food composition may have permanent effects and it is suggested that, in the rat, this may be due to structural alterations in the brain at a time when it is still differentiating. Such changes are irreversible.

How important are carnitine and ketones for the newborn infant?

The newborn oxidizes a large amount of fat. This is reflected in the slow rise of plasma levels of ketones and of total carnitines and acylcarnitines. Feeding a diet devoid of carnitine (soy-based formulas, total parenteral nutrition [TPN] ) rapidly results in a fall in plasma total carnitine levels, whereas in the adult such a fall is observed only after a prolonged time of TPN. This suggests that carnitine synthesis in the newborn is less efficient than in the adult. Gluteal adipocytes in the newborn show a rise in carnitine content and in the activity of carnitine transferases soon after birth, when values are higher than in the adult. Their respiration, lipolysis, and triglyceride formation are enhanced by L-carnitine and inhibited by D-carnitine. This is not so in the adult. Addition of L-carnitine to soybean-based formulas decreases plasma triglyceride and free fatty acid levels in premature infants, who have lower carnitine levels at birth than full-term babies. In pregnant women plasma total carnitine levels are significantly depressed. maternal urinary excretion of total carnitine decreases as gestational age increases, and less is also found in amniotic fluid. Plasma levels of total carnitines and acylcarnitine are the same (or higher) in fetal as in maternal plasma. It is concluded that carnitine may be of particular importance to the neonate and that adding it to foods lacking this substance may be advantageous.

Serial measurement of plasma cholesterol and lecithin:cholesterol acyl transferase activity in adults receiving total parenteral nutrition

The effect of total parenteral nutrition (TPN) containing approximately 800 ml Nutralipid daily on plasma cholesterol and lecithin:cholesterol acyl transferase (LCAT) activity was studied in 11 adult hospital patients. LCAT was assayed using an endogenous (S/N) and an artificial (ASA) substrate to differentiate between altered plasma substrate composition (which would influence the S/N method) and enzyme quantity (measured by the exogenous ASA method). Total cholesterol levels increased significantly during TPN, but generally remained within normal range. In comparison to laboratory reference values, free cholesterol was elevated and high-density lipoprotein cholesterol and ASA LCAT activity was reduced in patients before the start of TPN and remained unaltered by the TPN regime. S/N LCAT activity was normal and not altered by TPN. Since changes in plasma high-density lipoprotein and free cholesterol and ASA LCAT were present in patients before TPN, it must be concluded that they resulted from the underlying disease rather than the TPN per se. Longitudinal analyses showed that during the first 21 days of TPN nine patients showed a further fall in ASA LCAT and a rise in free cholesterol, thereafter ASA LCAT activity rose and free cholesterol fell despite continuation of TPN. It is suggested that ASA is a more reliable indicator of cholesterol esterification than S/N and that change in LCAT activity, although not caused by TPN, was related to the altered plasma lipid profile in the patients studied.

Carnitine and carnitine transferases in the intestinal mucosa of suckling rats

Carnitine acetyltransferase and palmitoyltransferase activity in the mucosa of the small intestine of rats rises after birth and falls at the time of weaning. The carnitine contents of the mucosa (free, acetyl-, palmitoyl- and total) decrease postnatally, reaching adult levels at the time of weaning. Orally administered 14C-carnitine is only slowly absorbed so that radioactivity is still high in plasma and organs 6 h later, whereas label given subcutaneously disappears from the plasma and tissues more rapidly. The intestinal mucosa also takes up carnitine from 14C-carnitine administered subcutaneously. It is concluded that carnitine plays an important role in the gut of suckling rats.

Effect of litter size on plasma cholesterol and insulin and some liver and adipose tissue enzymes in adult rodents

Rats and mice were raised in litters of 4 or 14 per mother. Plasma levels of cholesterol and insulin were found to be elevated later in life in those raised in small litters. Hepatic 3-hydroxy-3-methylglutaryl-CoA reductase activity in rats was higher in large than in small litters on day 60 but not on day 240. In adipose tissue activity was higher in the small litters. The activities of phosphoenolpyruvate carboxy-kinase in liver and of fatty acid synthetase in adipose tissue were higher in large than in small litters later in life. It is concluded that early quantitative changes in food intake have permanent late effects.

Fructose-1,6-biphosphatase activity in the intestinal mucosa of developing rats

Fructose-biphosphatase (EC 3.1.3.11) activity was determined in the proximal and distal parts of the small intestinal mucosa of rats 1-30 days of age. Activity was found to increase to a maximum on about the 10th postnatal day and then to decrease. It was always higher in the proximal than in the distal portion of the gut. The enzyme showed a wide range of pH optimum around 7.0 and was inhibited by AMP. In 10-day-old rats activity determined 24 or 48 h after a single injection of cortisone or triiodothyronine was significantly decreased. This effect was no longer found for cortisone in 14-day-old animals. Weaning 18-day-old rats to a high-fat diet for 5 or 7 days delayed but did not prevent the usual decrease in activity seen at weaning.

[Origin and significance of a thermostable granulocyte antigen]

In 1972 the thermostabile antigen of granulocytes was for the first time isolated by Thoss and Abendroth from punctates of the joint of patients with rheumatoid arthritis. Its origin from mature neutrophil granulocytes was ascertained by fluorescence-microscopic investigations. In the present paper the existence of thermostabile antigen of granulocytes in neutrophil granulocytes could be confirmed. The fluorescence pattern of neutrophil granulocytes of healthy persons did not show any differences in comparison to patients with inflammatory or myeloproliferative diseases as well as granulocytes from punctates of the joint or sternal marrow. With the help of punctates of the lymph-nodes the presence of thermostabile antigens of granulocytes in cells of the lymphatic system could be excluded. In smears of the sternal marrow positive fluorescence could be proved in the myelopoesis in neutrophil metamyelocytes. Quantitative investigations in inflammatory and myeloproliferative diseases as well as in granulocytopenias showed that the TSGA -serum values of the numbers of granulocytes go parallel. In punctates of the joint of patients with rheumatoid arthritis we found concentrations of thermostabile antigens of granulocytes which up to 50-fold were above the normal values of the serum. There was a close correlation to the number of granulocytes in the synovial fluid and to the cytological local activity. The TSGA -level can be regarded as indicator of granulocytic activation.

Oral L-carnitine administration after jejunoileal by-pass surgery

Jejunoileal bypass surgery was performed on 14 morbidly obese women. Seven were treated with 3/g/day oral L-carnitine for ten days before surgery and for another ten days at six weeks following surgery. The other seven were not treated with carnitine. Carnitine administration was found to be without effect on plasma lipids, free fatty acids and ketones and on all other tested indicators. However, plasma levels of carnitine and the rate of urinary elimination of carnitine both after treatment and after an acute oral load were increased before and after surgery, indicating that carnitine was well absorbed by the shortened gut. Rate of elimination of short chain carnitine esters via the urine was also elevated after treatment. Surgery resulted in a marked decrease of plasma lipids but in no change in apolipoprotein A and B concentrations.

Cholesterol oxidation and 7 alpha-hydroxylation during postnatal development of the rat

The activity of rat hepatic cholesterol 7 alpha-hydroxylase is low in the suckling period and rises at weaning. The oxidation of intraperitoneally administered 26(-14)C-cholesterol to 14CO2 is also low in suckling rats and increases with age as does the radioactivity in the plasma. In contrast, propionic acid oxidation to CO2 is much more rapid, suggesting that the side chain cleavage of cholesterol is not a rate-limiting process.

Regulation of phosphoenolpyruvate carboxykinase during postnatal development in the rat

Phosphoenolpyruvate carboxykinase (EC 4.1.1.49) (PEPcK) activity is high in the liver, brown fat, and small intestinal mucosa of suckling rats. Starvation results in a rise in hepatic activity in newborn and older animals, but a fall in brown fat from rats younger than 14 days. At that age, activity rises in all three tissues on fasting. Both triiodothyronine (T3) and dexamethazone depress activity in gut and (as previously reported) in brown fat, but elevate it in liver. Cold exposure also has a similar effect. Both alpha-antagonist and agonist injections result in elevated hepatic activity. T3 given together with these more than doubles the effect of either drug or T3 given alone. In brown fat only antagonists decrease PEPcK activity, whereas in gut both agonists and antagonist have an inhibitory effect. It is concluded that PEPcK activity in the three tissues responds differently to the same stimuli with gut mucosa being more similar to, but not the same as, brown fat than to liver.

Effect of intralipid on total and high-density lipoprotein cholesterol levels in newborns and infants

Even in very small premature infants (less than 1,000 g) intravenous feeding with Intralipid results in an elevation of total and a fall of high-density lipoprotein (HDL) cholesterol levels. If oral feeding occurs while Intralipid is given, HDL cholesterol levels rise again. A positive correlation was found between levels of total cholesterol and the amount of fat administered. A negative relationship was evident between the level of total cholesterol and that of HDL and between the latter and the amount of fat consumed.

Cholesterol synthesis in the small intestine and adipose tissue of suckling rats: the effect of litter size

Rats were raised in large (14/dam), medium (8/dam) and small (4/dam) litters. The rate of in vitro synthesis of cholesterol from 3H2O in the proximal and distal parts of the small intestine decreased from birth to a low 14 days later and then increased again by day 21. The rate of synthesis in both parts of the gut on day 6 after birth was lowest in the 14/dam group. On day 21 after birth the rate was highest in the 14/dam group in the proximal and lowest in the distal gut. Thus in the early postnatal period low rates of intestinal cholesterol synthesis correlate with low plasma cholesterol values. In white adipose tissue the low rate of cholesterol synthesis remained unaltered up to day 21 in the 8/dam, and 4/dam groups. However, it continuously increased in the 14/dam group being about threefold higher than in the other two groups on day 21.