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F David

Publications and source records attributed to F David.

At least 127 records · Page 7Linked to original sources
PubMed1988

Pseudoketogenesis in the perfused rat heart.

Ketogenesis is usually measured in vivo by dilution of tracers of (3R)-hydroxybutyrate or acetoacetate. We show that, in perfused working rat hearts, the specific activities of (3R)-hydroxybutyrate and acetoacetate are diluted by isotopic exchanges in the absence of net ketogenesis. We call this process pseudoketogenesis. When hearts are perfused with buffer containing 2.3 mM of [4-3H]- plus [3-14C]acetoacetate, the specific activities of [4-3H] and [3-14C]acetoacetate decrease while C-1 of acetoacetate becomes progressively labeled with 14C. This is explained by the reversibility of reactions catalyzed by mitochondrial 3-oxoacid-CoA transferase and acetoacetyl-CoA thiolase. After activation of labeled acetoacetate, the specific activity of acetoacetyl-CoA is diluted by unlabeled acetoacetyl-CoA derived from endogenous fatty acids or glucose. Acetoacetyl-CoA thiolase partially exchanges 14C between C-1 and C-3 of acetoacetyl-CoA. Finally, 3-oxoacid-CoA transferase liberates weakly labeled acetoacetate which dilutes the specific activity of extracellular acetoacetate. An isotopic exchange in the reverse direction is observed when hearts are perfused with unlabeled acetoacetate plus [1-14C]-, [13-14C]-, or [15-14C]palmitate; here also, acetoacetate becomes labeled on C-1 and C-3. Computations of specific activities of (3R)-hydroxybutyrate, acetoacetate, and acetyl-CoA yield minimal rates of pseudoketogenesis ranging from 19 to 32% of the net uptake of (3R)-hydroxybutyrate plus acetoacetate by the heart.

3-Hydroxybutyric Acid↗
PubMed1988

Interference of 3-hydroxyisobutyrate with measurements of ketone body concentration and isotopic enrichment by gas chromatography-mass spectrometry.

Concentrations and 13C2 molar percentage enrichments of blood R-3-hydroxybutyrate and acetoacetate are measured by selected ion monitoring gas chromatography-mass spectrometry. Samples are treated with NaB2H4 to reduce unlabeled and labeled acetoacetate to corresponding deuterium-labeled RS-3-hydroxybutyrate species. Only the gas chromatographic peak for the tert-butyldimethylsilyl derivative of 3-hydroxybutyrate needs to be monitored. The various compounds are quantitated using an internal standard of RS-3-hydroxy-[2,2,3,4,4,4-2H6]-butyrate. Concentrations of ketone bodies are obtained by monitoring the m/z 159 to 163 fragments of tert-butyldimethylsilyl derivatives of labeled and unlabeled 3-hydroxybutyrate species. High correlations were obtained between ketone body concentrations assayed (i) enzymatically with R-3-hydroxybutyrate dehydrogenase and (ii) by gas chromatography-mass spectrometry. The limit of detection is about 10 nmol of substrate in blood samples. The current practice of monitoring the m/z 275 to 281 fragments overestimates the concentration of endogenous R-3-hydroxybutyrate, due to co-elution of 3-hydroxyisobutyrate, a valine metabolite. The method presented is used to measure ketone body turnover in vivo in 24-h-fasted dogs.

3-Hydroxybutyric Acid↗
PubMed1988

Familial Alzheimer's disease (FAD): co-segregation between alleles at the D21S11 DNA marker and the FAD gene in a particular pedigree.

Segregation studies of Alzheimer's disease (AD) gene and a cloned DNA probe (D21S11), which detects an EcoRI restriction fragment length polymorphism for a sequence located in the medial part of the long arm of chromosome 21, are reported in a large pedigree, in which AD is transmitted as an autosomal dominant mendelian trait. In this pedigree, the AD gene co-segregation with one of the alternative alleles at the probe raises the possibility of using such a marker for presymptomatic diagnosis of individuals at risk for the disease.

Alzheimer Disease↗
PubMed1988

Absence of a close linkage between Alzheimer's disease susceptibility gene and a polymorphic DNA probe coding for beta-amyloid.

The hypothesis of a connection between Alzheimer's disease (AD) gene and the probe coding for beta-amyloid (beta-A), located on chromosome 21, was investigated in a large study group from Calabria, in which AD was transmitted as an autosomal dominant Mendelian trait. Segregation analysis of one EcoRI restriction polymorphism of beta-A, after molecular hybridization with a long cDNA probe of DNAs from key-individuals in the study group, determined that there was not a close connection between AD and beta-A.

Alzheimer Disease↗
PubMed1988

[Absence of a close linkage between Alzheimer's disease and the polymorphic probe coding for superoxide dismutase 1].

The hypothesis of a tight linkage between Alzheimer's disease (AD), a presenile dementia, and the probe coding for superoxide dismutase 1 (SOD 1), located on chromosome 21 at 21q22, has been investigated in a large family originating from Calabria, in which AD is transmitted as an autosomal dominant mendelian trait. Analysis of the Msp I restriction polymorphism, after molecular hybridization with the probe of DNAs coming from 22 subjects of the pedigree, allowed to the demonstrate that there wasn't any tight linkage between AD and the marker studied.

Alleles↗
PubMed1987

Contribution of the shunt pathway of mevalonate metabolism to the regulation of cholesterol synthesis in rat liver.

The modulation of the shunt pathway of mevalonate metabolism (Edmond, J., and Popják, G. (1974) J. Biol. Chem. 249, 66-71) has been studied in livers from fed, starved, and diabetic rats perfused with a physiological concentration (300 nM) of [5-14C] + [5-3H]mevalonate. Shunt activity was measured by (i) production of 14CO2 (corrected for loss of label by exchange reactions) and (ii) production of 3H2O. Contribution of exogenous mevalonate to total mevalonate production (0.06-0.11%) was assessed in parallel experiments by the incorporation of 3H2O into sterols. Inhibition of non-saponifiable lipid synthesis by starvation and diabetes is not associated with an inhibition of mevalonate production but with a major increase in shunting (7-34%) of sterol-bound mevalonate. The shunt pathway of mevalonate metabolism appears to participate in the regulation of cholesterol synthesis.

Animals↗
PubMed1987

Production of acetone and conversion of acetone to acetate in the perfused rat liver.

The utilization of millimolar concentrations of [2-14C]acetone and the production of acetone from acetoacetate were studied in perfused livers from 48-h starved rats. We devised a procedure for determining, in a perfused liver system, the first-order rate constant for the decarboxylation of acetoacetate (0.29 +/- 0.09 h-1, S.E., n = 8). After perfusion of livers with [2-14C]acetone, labeled acetate was isolated from the perfusion medium and characterized as [1-14C]acetate. No radioactivity was found in lactate or 3-hydroxybutyrate. After 90 min of perfusion with [2-14C]acetone, the specific activity of acetate was 30 +/- 4% (n = 13) of the initial specific activity of acetone. We conclude that, in perfused livers from 2-day starved rats, acetone metabolism occurs for the most part via free acetate.

Acetates↗
PubMed1987

Compartmentation of 14CO2 in the perfused rat liver.

The specific activity of the mitochondrial CO2 + bicarbonate system has been measured in perfused livers using the specific activities of urea and acetoacetate derived from 2-ketoisocaproate catabolism. Label was supplied either as NaH14CO3, 2-keto[1-14C]isocaproate, [1-14C]pyruvate, [1-14C]glutamine, or [14C]formate. With labeled bicarbonate, pyruvate, or 2-ketoisocaproate, the specific activities of effluent bicarbonate, urea, and acetoacetate were equal (acetoacetate was labeled only on C-1). In the presence of [14C]formate, the specific activity of acetoacetate was double that of urea. Acetazolamide (0.2 mM), an inhibitor of carbonic anhydrase, decreased the specific activities of urea and acetoacetate labeled from NaH14CO3 and increased the specific activities of urea and acetoacetate labeled from the other tracers. We conclude that: acetoacetate derived from 2-ketoisocaproate is, like urea, an index of the specific activity of mitochondrial CO2 in liver, carbonic anhydrase activity equalizes the specific activities of the CO2 + bicarbonate system on both sides of the mitochondrial membrane, and a fraction of [14C] formate-derived 14CO2 appears to be generated in a mitochondrial compartment, in the close vicinity of methylcrotonyl-CoA carboxylase.

Acetazolamide↗
PubMed1987

Impairment of immunogenicity by antigen presentation in liposomes made from dimyristoylphosphatidylethanolamine linked to the secretion of prostaglandins by macrophages.

The induction of antibody response in syngeneic rats by the Gross virus cell surface antigen (GCSAa) was dependent on the presentation of GCSAa into liposomes made from distearoylphosphatidylcholine (DSPC). GCSAa liposomes made from dimyristoylphosphatidylethanolamine (DMPE) were nonimmunogenic, even when used as anamnestic immunogens. Spleen cells, from rats twice immunized with GCSAa-DSPC-liposomes and used to transfer the anti-GCSAa immune response into naive recipients after a tertiary immunostimulation in vitro in the presence of naive peritoneal exudate cells (PEC), responded to soluble GCSAa only after irradiation at 500 rds and to GCSAa-DMPE-liposomes only when indomethacin was added during the in vitro stimulation. The preincubation of these cells with empty DMPE liposomes or the addition of supernatant from PEC fed with DMPE liposomes abrogated the response to GCSAa-DSPC liposomes. Using a specific radioimmunoassay, prostaglandin E2 was demonstrated to be produced by PEC when fed with DMPE liposomes, and not when fed with DSPC liposomes. This prostaglandin E2 secretion by PEC induced by DMPE liposomes was inhibited by indomethacin.

Animals↗
PubMed1987

[Absence of linkage between Alzheimer's disease and a polymorphic probe of the long arm of chromosome 21].

The hypothesis of an eventual linkage between Alzheimer's disease (AD), a presenile dementia, and the genomic probe GMG 21 S3, located on the long arm of chromosome 21, has been investigated in a large family originating from Calabria, in which AD is transmitted as an autosomal dominant mendelian trait. Analysis of the Bgl II restriction polymorphism, after molecular hybridization with the probe, of DNAs coming from 28 subjects of a pedigree, from which 10 individuals are affected, allowed to demonstrate that there wasn't any linkage between AD and the marker studied.

Alzheimer Disease↗
PubMed1986

Determination of the concentration and specific activity of acetone in biological fluids.

The concentration of acetone dissolved in liver perfusion medium was determined by injection of the sample into a gas chromatograph equipped with a Carbopack/Carbowax-packed glass column. Interference from labile acetoacetate which readily decomposes to acetone was eliminated by treating the samples with NaBH4 prior to the analysis. Acetone was detected and quantified as 2-propanol. Separation of labeled 2-propanol in the sample by high-performance liquid chromatography allowed the determination of its specific activity. These methods make possible the convenient and rapid determination of acetone concentration and specific activity in biological samples.

1-Propanol↗
PubMed1986

Renal prostaglandins E2 and F2 alpha throughout normal human pregnancy.

Twenty-five normal pregnant women were studied sequentially at 4-week intervals, beginning from weeks 8-16 until delivery. In eighteen women the study was repeated 6 weeks after delivery. The 24-h urinary excretion of PGE2 and PGF2 alpha, plasma renin activity (PRA), plasma aldosterone and fractional excretion of sodium (FENa) were measured at each visit. PGE2 and PGF2 alpha increased progressively throughout pregnancy (867 +/- 81 and 1048 +/- 94 ng 24 h-1 respectively, before week 15 and 1581 +/- 175 and 2625 +/- 305 ng 24 h-1, respectively, after week 35) and returned to normal values 6 weeks after delivery (748 +/- 107 and 1503 +/- 165 ng 24 h-1, respectively). PRA and aldosterone increased in a similar fashion, but values of prostaglandins did not correlate with those of PRA or aldosterone. PGE2 correlated directly with FENa but this correlation was weak. These results may suggest that tubulo-interstitial prostaglandins play a role in the regulation of sodium homeostasis during pregnancy.

Adult↗
PubMed1985

Characterization of monoclonal antibodies against prostaglandin E2: fine specificity and neutralization of biological effects.

The specificity and heterogeneity of the immune response of BALB/c mice immunized with prostaglandin E2 (PGE2) coupled to thyroglobulin was studied. All the animals (n = 50) responded to PGB2, a transformation product of PGE2. However, following repeated injections most of the animals (n = 30) were also able to respond to PGE2. Cellular hybridizations were performed and five anti-PGE2 monoclonal antibodies were isolated and analysed. They are mainly directed against the ring and the omega-chain of PGE2 but their specificity toward the alpha-chain is more limited. The association constants are greater than to 1 X 10(9) M-1. The monoclonal antibody 8E.57.71 (Ka = 1.3 X 10(10) M-1) is particularly convenient for sensitive radioimmunoassays (detection limit 25pg/ml, when iodinated tracer is used). Anti-PGE2 monoclonal antibodies were found to neutralize the specific binding of [3H]PGE2 to rat brain hypothalamic receptors and to inhibit the PGE2 induction of rat fundus muscular contraction.

Animals↗