Mechanisms of Pathogenesis in Listeria monocytogenes Infection III. Carbohydrate Metabolism

Several enzymes and metabolites concerned with carbohydrate metabolism were examined in mice infected with Listeria monocytogenes. Liver glycogen and glucose decreased parallel to severity of infection. The concentration of glucose in the blood fell to abnormally low levels with a hypoglycemia being most evident at 72 hr. There was a significant decrease in the activity of hepatic uridine diphosphate glucose-glycogen transglucosylase. This decrease in enzymatic activity correlated with the rate of glycogen depletion. Phosphorylase activity declined in a similar fashion, contraindicating enhanced glycogenolysis as the mechanism responsible for glycogen depletion. Although glucose-6-phosphatase decreased throughout the infection period, it did not appear to be the major metabolic defect causing hypoglycemia in Listeria-infected mice. Further distortion of carbohydrate metabolism was indicated by findings of increased levels of pyruvate and lactate in the blood of infected animals.     

Stimulation of monocyte precursors in vivo by an extract from Listeria monocytogenes.

A water-soluble monocytosis-producing activity (MPA) extracted from Listeria monocytogenes was found to stimulate proliferation of promonocytes in vivo. Mice were pulse-labelled for 2 h with tritiated thymidine ([3H]TdR) at various times after intraperitoneal injection of MPA. Autoradiography of bone marrow cells revealed an increased labelling index of promonocytes of MPA-treated mice which was maximum 8 h after the MPA injection. Mice labelled with [3H]TdR 8 h after MPA injection developed a monocytosis at the expected time (peak at 48 h) and the blood monocytes were found to be highly labelled. Both the generation time of monocyte precursors and the halftime of blood monocytes were found to be shorter than the corresponding values in control mice.     

Regulation of cell growth of a progestin-dependent murine mammary carcinoma in vitro: progesterone receptor involvement in serum or growth factor-induced cell proliferation

Primary cultures of the medroxyprogesterone acetate-induced mouse mammary tumor line C4-HD are stimulated by medroxyprogesterone acetate (MPA) or progesterone. Serum obtained from ovariectomized, MPA-treated animals (OVX-MPA) exerts a stimulatory effect that is significantly higher than that induced by serum obtained from OVX mice with the exogenous addition of MPA, suggesting the involvement of MPA-induced serum factors potentiating the proliferative effect of MPA. The object of this paper is to further explore the stimulatory effect of mouse serum and to investigate the role of aFGF and bFGF on cell proliferation. The role of PR as possible mediators was tested using two different antiprogestins and antisense oligodeoxynucleotides of PR A isoform. Serum was obtained from OVX untreated or MPA-treated mice and was charcoalized and/or heat-inactivated. The effect of MPA or mifepristone at 10 nM concentrations was tested. Charcoalization and heat inactivation exerted a stimulatory effect (P<0.01) when OVX-serum was used. This effect was potentiated by MPA. Charcoalized OVX-MPA serum induced a significant inhibition of cell proliferation that was restored by the exogenous addition of MPA or by heat inactivation. Mifepristone induced an inhibition of ³H-thymidine uptake when OVX-MPA serum was used. These results suggest that serum factors activated by different manipulations may replace the stimulatory effect of MPA. When charcoalized fetal calf serum (chFCS) was used, a higher proliferative activity was obtained using higher serum concentrations. Mifepristone and onapristone 10 nM also inhibited this effect. aFGF and bFGF 100 ng/ml were both able to stimulate ³H-thymidine uptake. MPA exerted an additive effect. Mifepristone 10 nM inhibited bFGF and MPA+bFGF induced cell proliferation. Antisense oligodeoxynucleotides of PR (ASPR) were used to further confirm the participation of PR in the proliferative pathway of these cells. They inhibited serum and bFGF-induced cell proliferation in a specific dose-dependent manner. Our results suggest that PR play a central role in proliferation and suggest the existence of a cross-talk between steroid and growth factor signaling pathways.     

Effect of exogenous progestogens on plasma concentrations of the oxytocin-associated neurophysin and 13,14-dihydro-15-keto-prostaglandin F in intact and ovariectomized ewes over the time of expected luteal regression

Plasma concentrations of the prostaglandin F metabolite 13,14-dihydro-15-keto-prostaglandin F (PGFM), the oxytocin-associated neurophysin (OT-N) and progesterone were monitored by radioimmunoassay (RIA) in five ewes sampled from the jugular vein at hourly intervals between 0700-1900 h from Days 12-16 of the estrous cycle. These hormones were also determined in plasma samples collected at similar times from five intact and five ovariectomized ewes given twice daily injections of medroxyprogesterone acetate (MPA) over Days 10 to 20 after the last observed estrus. In both the control and intact MPA-treated ewes, coincident surges of OT-N and PGFM were observed in jugular plasma during the time of luteal regression. No significant differences were noted in the number and amplitude of OT-N and number of PGFM peaks between the control and intact MPA-treated animals, although in the latter the amplitude of the PGFM peaks was significantly reduced (P less than 0.01). No marked surges in the plasma concentrations of PGFM or OT-N were observed in the ovariectomized ewes given exogenous MPA. This latter finding is consistent with previous proposals, suggesting that the ovaries are a major source of oxytocin in the ewe. In addition, the observation that exogenous progestogens in the intact ewes did not influence the number and peak height of the OT-N surges, indicates that a fall in progesterone levels during the normal cycle is not obligatory for oxytocin release although it may facilitate the release of uterine PGF2 alpha.     

Influence of age and exercise training on lipid metabolism in Fischer-344 rats

The influence of training on fatty acid and glyceride synthesis by liver and adipose tissue homogenates of young and old Fischer-344 rats was examined. Four groups of rats (10 animals/group) were studied: young untrained, young trained, old untrained, and old trained. Training of each group was for 10 wk at 75% maximal O2 uptake. Young rats were killed at 6 mo of age and old rats were killed at 27 mo of age. Fatty acid synthesis was assessed by measuring the activities of acetyl-CoA carboxylase, fatty acid synthase, ATP citrate-lyase, "malic" enzyme, and glucose-6-phosphate dehydrogenase. Glyceride synthesis was evaluated by determining the rate of incorporation of [14C]glycerol 3-phosphate into lipids. In addition, lipoprotein lipase activity was measured in acetone-ether powders of adipose tissue from the four groups of rats. In liver, training had no effect on fatty acid or glyceride synthesis in either group. However, aging caused a significant decrease in the activities of four of the lipogenic enzymes but had no effect on glyceride synthesis. Training caused an increase in fatty acid synthase and glyceride synthesis in adipose tissue, and aging decreased lipoprotein lipase activity. It was concluded that training enhances the synthetic capacity of lipids by adipose tissue but that aging had a more profound effect in that the activities of the enzymes involved in these processes were lower in the old rats. Furthermore, the decreased activity of lipoprotein lipase in the older rats may explain the higher plasma triglyceride levels that were observed in these animals.     

Mycophenolic acid inhibits the degranulation of rat peritoneal mast cells.

The effect of mycophenolic acid (MPA), a potent inhibitor of inosine monophosphate dehydrogenase, on the degranulation of rat peritoneal mast cells (RMC) was studied. RMC were pretreated for 48 hr with 0.1-10 microM MPA before the cells were sensitized with IgE and triggered with specific Ag. The net amount of [3H]5-HT released from granules was decreased by 44 and 32% with 1 and 10 microM MPA treatment, respectively. MPA inhibition of degranulation was completely reversed by the addition of 30 microM guanosine to the incubation medium. There was no difference in the apparent number or affinity of IgE binding sites between control and MPA-treated RMC. MPA pretreatment also had no effect on the IgE receptor-mediated production of PGD2 in RMC. These results suggest that depletion of intracellular GTP pools by MPA can disrupt the signaling between the IgE receptor and the secretory granules and that, under these same conditions, the release and metabolism of arachidonic acid are unaffected.     

Effects of training on glucose metabolism of gluconeogenesis-inhibited short-term-fasted rats

To evaluate the effects of endurance training on gluconeogenesis and blood glucose homeostasis, trained as well as untrained short-term-fasted rats were injected with mercaptopicolinic acid (MPA), a gluconeogenic inhibitor, or the injection vehicle. Glucose kinetics were assessed by primed-continuous venous infusion of [U-14C]- and [6-3H]glucose at rest and during submaximal exercise at 13.4 m/min on level grade. Arterial blood was sampled for the determination of blood glucose and lactate concentrations and specific activities. In resting untrained sham-injected rats, blood glucose and lactate were 7.6 +/- 0.2 and 1.3 +/- 0.1 mM, respectively; glucose rate of appearance (Ra) was 71.1 +/- 12.1 mumol.kg-1.min-1. MPA treatment lowered blood glucose, raised lactate, and decreased glucose Ra. Trained animals had significantly higher glucose Ra at rest and during exercise. At rest, trained MPA-treated rats had lower blood glucose, higher blood lactate, and similar glucose Ra and disappearance rates (Rd) than trained sham-injected animals. Exercising sham-injected untrained animals had increased blood glucose and glucose Ra compared with rest. Exercising trained sham-injected rats had increased blood glucose and glucose Ra and Rd but no change in blood lactate compared with untrained sham-injected animals. In the trained animals during exercise, MPA treatment increased blood lactate and decreased blood glucose and glucose Ra and Rd. There was no measurable glucose recycling in trained or untrained MPA-treated animals either at rest or during submaximal exercise. There was no difference in running time to exhaustion between trained and untrained MPA-treated rats.(ABSTRACT TRUNCATED AT 250 WORDS)     

Flight metabolism in Panstrongylus megistus (Hemiptera: Reduviidae): the role of carbohydrates and lipids

The metabolism of lipids and carbohydrates related to flight activity in Panstrongylus megistus was investigated. Insects were subjected to different times of flight under laboratory conditions and changes in total lipids, lipophorin density and carbohydrates were followed in the hemolymph. Lipids and glycogen were also assayed in fat body and flight muscle. In resting insects, hemolymph lipids averaged 3.4 mg/ml and significantly increased after 45 min of flight (8.8 mg/ml, P < 0.001). High-density lipophorin was the sole lipoprotein observed in resting animals. A second fraction with lower density corresponding to low-density lipophorin appeared in insects subjected to flight. Particles from both fractions showed significant differences in diacylglycerol content and size. In resting insects, carbohydrate levels averaged 0.52 mg/ml. They sharply declined more than twofold after 15 min of flight, being undetectable in hemolymph of insects flown for 45 min. Lipid and glycogen from fat body and flight muscle decreased significantly after 45 min of flight. Taken together, the results indicate that P. megistus uses carbohydrates during the initiation of the flight after which, switching fuel for flight from carbohydrates to lipids.     

Glucose metabolism by isolated fat cells from sloth.

Glucose metabolism by sloth fat cells with and without addition of insulin was investigated. The data were compared to the results obtained with rat fat cells incubated under the same experimental conditions. Sloth fat cells showed a very low glucose oxidation to 14CO2 and incorporation into total lipids. The glucose incorporated into lipids is mainly in the glyceride-glycerol moiety. Addition of insulin did not produce an increase on glucose oxidation and a slight increase in the incorporation into total lipids was observed. Since it has been reported that sloths have a very low rate on thyroxine secretion, the results are discussed in relation to data in the literature on carbohydrate and lipid metabolism in hypothyroid animals.     

Effects of diet and activity on lipid levels of adult Mediterranean fruit flies

Abstract. The objectives of this study were to determine whether adult Mediterranean fruit flies, Ceratitis capitata Wiedeman (Diptera: Tephritidae), are capable of synthesizing lipids, and whether adult diet affects this ability.Lipid levels in females fed protein and carbohydrate or carbohydrate alone declined significantly from emergence to the fourth day of life and then rose back to teneral levels on the fifth day, before oviposition took place on the sixth day.In males fed protein and carbohydrate, lipid levels initially declined as males aged and then stabilized.In carbohydrate-fed males lipid levels declined following emergence and recovered somewhat by the sixth day.Lipid levels declined significantly when flies underwent post-emergence starvation, but after substantial feeding on the above-mentioned diets they eventually (within 6–7 days) reached teneral levels in all experimental groups.Multivariate analysis of variance revealed that differences in lipid contents are primarily related to the flies' age, which corresponds to the various sex-specific activities these flies exhibit.Average lipid investment in eggs was found to equal teneral lipid levels in females.Without lipogenic abilities, oviposition would completely deplete female lipid reserves.We conclude that adult medflies are capaple of lipid synthesis, and that this capability is modulated by individual and sex-specific activity patterns.     

Effect of diazepam treatment on metabolic indices in trained and untrained rats

Exercise training, like diazepam, is commonly employed as a means of reducing anxiety. Both diazepam and exercise training have been shown to modify carbohydrate and lipid metabolism as well as influence calcium metabolism in skeletal muscle. As receptor binding and thereby efficacy of diazepam has been demonstrated to be modulated by the lipid environment of the receptor, and changes in calcium levels can affect a number of intracellular signalling pathways, we sought to determine if the interaction of both chronic diazepam and exercise training would modify selected metabolic indices in an animal model. For this purpose, muscle and liver glycogen, blood glucose and plasma free fatty acids (FFA) were measured in sedentary, exercise trained and exercise trained, acutely exhausted animals. Alterations in lipid and carbohydrate metabolism were observed in all experimental groups. Diazepam treatment alone exerts metabolic consequences, such as elevated muscle glycogen and plasma FFA and depressed blood glucose levels, which are similar to those observed with exercise training. When animals are acutely exercised to exhaustion, however, differences appear, including a reduced rise in plasma FFA, which suggests that long-term diazepam treatment does influence exercise metabolism, possibly as a result of effects on the sympatho-adrenal system.     

Evaluation of Biochemical,Hematological and Parasitological Parameters of Protein-Deficient Hamsters Infected with Ancylostoma ceylanicum

Background

Hookworms infect millions of people worldwide and can cause severe clinical symptoms in their hosts. Prospective cohort studies in Brazil show high rates of hookworm reinfection in malnourished children compared to well-nourished children, despite previous treatment. Additionally, soil-transmitted helminth (STH) infections can worsen the nutritional status of affected populations. Therefore, this study aims to clarify the effects of host malnutrition during Ancylostoma ceylanicum infection and how this infection affects host physiological parameters using a hamster model.

Methodology/Principal Findings

Hamsters were divided into four experimental groups: normal diet or low-protein diet (also referred to as “malnourished”) and A. ceylanicum infection or no infection. More severe pathogenesis was observed in the infected malnourished group, as demonstrated by significant decreases in the hemoglobin concentration, erythrocyte number and packed-cell volume compared to the non-infected malnourished group. Greater numbers of adult parasites and eggs were observed in the malnourished group compared to the control group; however, the oviposition rate was lower in the malnourished group. In general, greater values of total lipids were observed in malnourished animals compared to control animals, including lipids excreted in the stool.

Conclusions

In this work, we have demonstrated that animals fed an isocaloric low-protein diet presented more severe pathogenesis when infected with A. ceylanicum. The increased lipid concentration in the liver and blood is related to the conversion of the excess carbohydrate into fatty acids that increase the concentration of triglycerides in general. Triglycerides were excreted in the feces, indicating that infection associated with malnutrition caused a greater loss of these molecules for this group of animals and confirming the hypothesis that both nutrition and infection are responsible for the malabsorption syndrome. Taken together, the results found in this work confirm the hypothesis that the nutritional condition of the host greatly influences the course of the infection.     

Mechanisms of Pathogenesis in Listeria monocytogenes Infection II. Characterization of Listeriosis in the CD-1 Mouse and Survey of Biochemical Lesions

Several physiological and biochemical changes which occur in CD-1 pathogen-free mice during the course of infection with Listeria monocytogenes strain A4413 have been examined. Mice injected with 10(4) to 10(6) organisms by the intraperitoneal route displayed a significant depression in weight gain. In contrast, at 24 hr after infection an increment in total liver weight averaging 0.1 g was observed. The ratios of liver to body weight increased throughout the observation period. As the severity of the infection increased, food intake, as well as total liver protein and nitrogen, showed a corresponding decrease, with the diminution being most evident immediately prior to the death of the animals. Blood urea nitrogen remained relatively constant for 24 hr and then increased continuously as the infection progressed to the acute stage. Total liver lipid increased until the death of the animals. At 72 hr postinfection, a significant decrease in oxidative phosphorylation was observed. Xanthine dehydrogenase activity increased, with maximal values obtained 72 hr after infection. Uric acid levels remained constant for 24 hr, diminished at 48 hr, and then increased until the death of the animals. After 24 hr, uricase activity showed a slight increase. This activity returned to within normal ranges at 48 hr and decreased as the infection progressed to the acute stage at 72 hr. The results support the hypothesis that at least a part of the cause of death is a derangement in hepatic purine and carbohydrate metabolism. The data are also consistent with the possibility of changes in iron transport in the infected mice.     

Some effects of medroxyprogesterone acetate on intermediary metabolism in rat liver.

This study examines the effects of MPA (medroxyprogesterone acetate) on some of the hepatic enzymes of carbohydrate and lipid metabolism in the rat, and compares these with the effects of cortisol and saline. Levels of reduced nicotinamide adenine dinucleotide phosphate (NADPH) were also measured. Intact mature female Wistar rats with average initial weight of 200 gms were injected with MPA (mO mg/kg IM) once a week for 4 weeks and were sacrificed 3 to 5 days after the last injection. Hydrocortisone (Solu-Cortef [R]) 40 mg/kg IM were given to cortisol-treated animals twice daily for 7 days. The animals were sacrificed 2-4 hours after the last dose was given. Normal saline (0.2 mg. IM) was injected in control animals twice a day. The method of Jellinek, Amako, and Willman was used to analyze NADPH. Liver samples were assayed for various enzymatic activities such as phophofructokinase (PFK); pyruvate kinase (PK), glycerol-3-phosphate dehydrogenase (G3PD), "malic" enzyme (ME), and glucose-6-phosphate dehydrogenase (G6PD). The methods of Colowick and Kaplan were used in enzymatic analyses. Lipogenic stimulation by MPA is indicated by increased levels of G3PD and ME, both of which are implicated in lipogenesis, as well as by NADPH. PFK, PK, and G6PD were all unaffected by the MPA regimen, suggesting that elevation of ME and NADPH activities may reflect increased amino acid conservation. The enzymatic pattern of MPA treatment shows lipogenesis and protein conservation, while that of cortisol regimen shows significantly lower levels of ME, G3PD, and PRK.     

Effects of cold stress on serum lipids, lipoproteins, and the activity of lecithin:cholesterol acyltransferase in rabbits

Effects of prolonged stress on lipid metabolism factors were studied for 9 weeks using four groups of young New Zealand rabbits. Two groups (A,B) were rendered atherosclerotic by administering 1% (w/w) cholesterol. One group (C) was subjected to cold stress together with one of the atherosclerotic groups (B); one group was used as control (N). At the end of treatment serum total cholesterol and total lipids of A and B increased significantly, while in stress group (C) a significant decrease was observed. HDL-C levels were reduced in all experimental groups. Triglycerides did not change in A, while they were reduced in both stress groups (C,B). Serum lecithin:cholesterol acyltransferase (LCAT) activity levels of B and C were decreased. Lipoprotein electrophoresis patterns showed a significant redistribution of percentage values in all experimental groups: %LDL-C increased and %VLDL-C decreased in all groups, %HDL-C declined in A and B and did not change in C. The combination of stress and atherosclerosis in rabbits elicits far greater alterations in lipid and lipoprotein profiles than stress or atherosclerosis alone. A stress and atherosclerotic diet combination may be a hazardous one in relation to CHD and atherosclerosis.     

Effect of long-term treatment with steroid hormones or tamoxifen on the progesterone receptor and androgen receptor in the endometrium of ovariectomized cynomolgus macaques

The progesterone receptor (PR) and androgen receptor (AR) belong to the nuclear receptor superfamily. Two isoforms of PR (A and B) have been identified with different functions. The expression of AR, each isoform of PR and their involvement in long-term effects on the endometrium after hormonal replacement therapy (HRT) or tamoxifen (TAM) treatment is not known. The aims of this study were to determine PR(A+B), PRB and AR distribution by immunohistochemistry in the macaque (Macaca fascicularis) endometrium. Ovariectomized (OVX) animals were orally treated continuously for 35 months with either conjugated equine estrogens (CEE); medroxyprogesterone acetate (MPA); the combination of CEE/MPA; or TAM. Treatment with CEE/MPA tended to down-regulate PR in the superficial glands, but increased it in the stroma. TAM treatment increased both the PR and PRB levels in the stroma. Overall, less than 20% of the cells were positive for the PRB isoform and less variation was observed after steroid treatment. AR was found in the stroma, mainly distributed in the basal layer of the endometrium in the OVX and steroid treated groups, but was absent in the TAM treated group. No AR was found in the glandular epithelium. The present data show that long-term hormone treatment affects the PR level, and also the ratio between PRA and PRB in the endometrium.     

Role of thyroid on testicular lipids in prepubertal, pubertal and adult rats. I. Hyperthyroidism

The influence of thyroxine-induced hyperthyroidism on testicular neutral and phospholipids was studied in prepubertal, pubertal and adult rats. Thyroxine treatment (25 micrograms/100 g body weight) for 1 month decreased testicular total lipids, total glyceride glycerols, total cholesterol and total phospholipids. Different classes of glyceride glycerol, cholesterol and phospholipid were also diminished due to thyroxine treatment. All classes of lipids returned to the euthyroid level after the withdrawal of thyroxine treatment. The data obtained in the present study suggest that thyroid hormones have a definite influence on testicular lipid metabolism in rats.     

Ameliorating effect of chromium administration on hepatic glucose metabolism in streptozotocin-induced experimental diabetes

Chromium has been recognized as an essential trace element that plays an important role in carbohydrate metabolism. However, the molecular mechanisms involved in its action are not clear. This study was undertaken to understand the mechanism of chromium action in experimental diabetes. Streptozotocin-induced diabetic animals were administered chromium as chromium picolinate (CrP) at a daily dose of 1 mg/kg body weight for a period of 4 weeks. It was observed that chromium complexed with picolinate was effective in lowering plasma glucose levels as well as was able to alleviate polyphagia, polydipsia, and weight loss in diabetic animals. Administration of chromium was also found to normalize glycogen content in liver of diabetic animals to near control levels. The reduction in plasma glucose levels by chromium was accompanied by increase in activity of glycolytic enzymes (e.g., glucokinase, phosphofructokinase, and pyruvate kinase) and by suppression in activity of gluconeogenic enzymes (e.g., glucose-6-phosphatase and phosphoenolpyruvate carboxykinase) in liver. Hepatic glucose uptake was found to be increased by chromium supplementation as demonstrated by decrease in Km and increase in Vmax values in diabetic animals. Chromium levels were lower in the liver of diabetic rats when compared with that of control rats. A negative correlation was observed between plasma glucose and chromium concentration in patients with diabetes. The data suggests that chromium supplementation as CrP is beneficial in correcting hyperglycemia, implying that the modulation of the glucose metabolism by chromium may be therapeutically beneficial in the treatment of diabetes.     

Mechanisms of pathogenesis in Listeria monocytogenes infection. I. Influence of iron

Sword, C. P. (The University of Kansas, Lawrence). Mechanisms of pathogenesis in Listeria monocytogenes infection. I. Influence of iron. J. Bacteriol. 92: 536-542. 1966.-The effects of ferric and ferrous iron as well as other cations on Listeria infection in mice were studied. Iron compounds caused a reduction in the ld(50) dose of Listeria, and, when added to a synthetic medium, proved stimulatory for in vitro growth of the organism. Bacterial counts on spleen and liver tissue from iron-treated mice showed that iron injections caused more rapid growth of bacteria and resulted in higher numbers of organisms in the tissue. The reticuloendothelial system did not appear to be impaired by this treatment. Immunized animals were not affected by iron treatment during challenge. Mice with experimentally induced hemolytic anemia showed increased susceptibility to listeriosis, whereas those treated with Desferal, a specific iron-chelating agent, appeared more resistant. Iron proved stimulatory for the avirulent strain, 9037-7, and resulted in an ld(50) of 1.3 x 10(4) organisms in iron-treated animals. Growth of L. monocytogenes and mortality from experimental infection appeared to be correlated with availability of iron to the bacteria. The results suggest that host iron metabolism may play a part in the onset and progress of Listeria infections.