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L Dupuis

Publications and source records attributed to L Dupuis.

36 records · Page 2Linked to original sources
PubMed1997

A caffeine/ryanodine-sensitive Ca2+ pool is involved in triggering spontaneous variations of Ca2+ in Jurkat T lymphocytes by a Ca(2+)-induced Ca2+ release (CICR) mechanism.

Caffeine and ryanodine triggered an increase in [Ca2+]i (73 +/- 22 and 61 +/- 18 nM, respectively) in Jurkat cell populations that was independent of external Ca2+. In individual cells, caffeine and ryanodine induced Ca2+ spikes. Jurkat cell populations initially exposed to caffeine did not respond further to ryanodine and vice versa, suggesting an overlap of the Ca2+ pool that was contained within the thapsigargin-sensitive Ca2+ reserve. [3H]ryanodine bound to a single class of sites of Jurkat microsomes (KD, 18.4 +/- 5.7 nM; Bmax, 24.3 +/- 7.7 fmol/mg protein). Photolytic release (Nitr5) of caged Ca2+ induced a time-dependent increase of Ca2+ in individual Jurkat cells. The profile of the release of Ca2+ was characterized, 1) by a kinetic (0.55 +/- 0.07 nM s-1) slower than the Ca2+ response to caffeine (3.93 +/- 0.66 nM s-1) or to ryanodine (3.96 +/- 0.94 nM s-1), 2) by a release of Ca2+ (131 +/- 43 nM) that slowly returned to baseline and during which low amplitude oscillations were present (room temperature) or Ca2+ spikes (37 degrees C) and, 3) by a lack of dependency on an influx of Ca2+. Inhibitors of CICR (ruthenium red and 1-octanol) prevented the photolysis-dependent increase in [Ca2+]i but not the InsP3-dependent Ca2+ response. Our data suggest that Jurkat T cells possess at least two Ca2+ pools, one that is sensitive to InsP3 and one that is insensitive. These two Ca2+ pools may be involved in a CICR that generates spontaneous Ca2+ spikes and oscillations in these cells.

1-Octanol↗
PubMed1996

Clustering of mutations in the biotin-binding region of holocarboxylase synthetase in biotin-responsive multiple carboxylase deficiency.

Holocarboxylase synthetase (HCS) catalyses the biotinylation of the four biotin-dependent carboxylases found in humans. A deficiency in HCS results in biotin-responsive multiple carboxylase deficiency (MCD). We have identified six different point mutations in the HCS gene in nine patients with MCD. Two of the mutations are frequent among the MCD patients analyzed. Four of the mutations cluster in the putative biotin-binding domain as deduced from the corresponding Escherichia coli enzyme and consistent with an explanation for biotin-responsiveness based on altered affinity for biotin. The two others may define an additional domain involved in biotin-binding or biotin-mediated stabilization of the protein.

Amino Acid Sequence↗
PubMed1996

Expression in insect cells and purification of a catalytically active recombinant human gastric lipase.

Human gastric lipase (HGL) cDNA was synthesized by RT-PCR amplification and cloned into the PVL 1392 baculovirus transfer vector. The recombinant transfer vector was cotransfected with a modified baculovirus DNA (Baculogold) which contains a lethal deletion. Cotransfection of baculovirus DNA with the recombinant transfer vector rescues the lethal deletion of this virus DNA and reconstitutes viable virus particles inside the transfected insect cells. BTI-TN-5B1-4 insect cells (also called High Five cells) were used to express recombinant HGL. The level of HGL secretion was approximately 32 mg/l of culture medium. The insect cells also accumulated HGL intracellularly, which indicated the existence of rate-limiting steps in the secretion of HGL. Therefore we investigated the effect of replacing the HGL signal peptide (SP) by other SP of secreted proteins. The honeybee melittin SP and the human pancreatic lipase (HPL) SP were tested. The fusion of HGL with HPL SP resulted in a 2-fold increase in the amount of lipase secreted from the insect cells. The recombinant active HGL was not processed at the expected cleavage site of the natural enzyme, however, but at residue +3. On the other hand, High Five cells transfected with the vector encoding HGL fused to the melittin SP did not secrete any detectable active HGL. Recombinant HGL was identified using the Western blot procedure with rabbit polyclonal antibodies. The protein migrated with an apparent molecular mass of 45 kDa under SDS-PAGE analysis (compared with 50 kDa in the case of natural HGL), indicating that the insect cells have only a limited capacity to glycosylate HGL. The maximum specific activities of the recombinant lipase were 434, 730 and 562 units/mg using long-chain (Intralipid), medium-chain (trioctanoylglycerol) and short-chain (tributyroylglycerol) triacylglycerols, respectively.

Amino Acid Sequence↗
PubMed1995

In vitro oxidative decarboxylation of L-2-hydroxy-4-methylthiobutanoic acid by L-2-hydroxy acid oxidase A from chicken liver.

The first step in the set of reactions responsible for the biological utilization of L-2-hydroxy-4-methylthiobutanoic acid, the methionine hydroxy analogue, in protein synthesis was investigated in vitro using pure L-2-hydroxy acid oxidase A from chicken liver. The reaction yielded no more than 20% of the corresponding alpha-keto acid, the well-known intermediate in methionine metabolism, and as much as 80% of the subsequent decarboxylation product, 3-methylthiopropionate, suggesting that L-2-hydroxy-4-methylthiobutanoic acid cannot be completely converted into methionine in vivo. It was therefore concluded that chicken liver L-2-hydroxy acid oxidase, a peroxisomal enzyme requiring flavin mononucleotide as a coenzyme, also has an oxidative decarboxylation activity in vitro, which was found to be NADH-dependent. The mechanism possibly underlying the successive conversion of the methionine hydroxy analogue into alpha-keto acid and 3-methylthiopropionate by this NADH:flavin oxidoreductase-decarboxylase activity is described.

Alcohol Oxidoreductases↗
PubMed1995

Tuberculosis, public health, and civil liberties.

The resurgence of tuberculosis confronts policy-makers with difficult legal and ethical questions about the proper use of state power and resources to protect public health. This chapter examines the implications of expanded use of invasive or coercive measures-including directly observed therapy, involuntary detention of noncompliant patients, and forced administration of medications--designed to reduce the risk of tuberculosis transmission and to ensure that those with TB are fully treated. These measures focus attention on the limitations of government power and obligation and on the delicate balance between the demands of civil liberty and the demands of public health.

Civil Rights↗
PubMed1993

The N-acylpeptide hydrolase from porcine intestine: isolation, subcellular localization and comparative hydrolysis of peptide and isopeptide bonds.

The N-acylpeptide hydrolase from porcine intestinal mucosa was 2000-fold purified by a five-step procedure. The resulting protein (about 300 kDa) is composed of four apparently identical N-acylated polypeptide chains. The enzyme activity was found to be equally distributed along the crypt-villus axis in the intestine and was characterized as a cytosolic protein. Besides the ability of porcine intestinal APH to cleave the first peptide bond in N-protected peptides (Km: 0.8 mM), it is worth stressing that the enzyme was also found to efficiently catalyze the hydrolysis of the isopeptide bond in N-epsilon-Ac-L-Met-L-Lys (Km: 0.7-1.1 mM). It is suggested that N-acylpeptide hydrolase might not only be involved in the catabolism of intracellular N-acylated protein catabolism but also be responsible for the biological utilization of N-acylated food proteins.

Alkaline Phosphatase↗
PubMed1990

Purification and some characteristics of chicken liver L-2-hydroxyacid oxidase A.

The isozyme A of L-2-hydroxyacid oxidase is a peroxisomal flavoenzyme that catalyzes the oxidation of short-chain aliphatic L-2-hydroxyacids in many tissues of higher organisms. A new purification procedure allowed us to obtain a 1400-fold purified enzyme from chicken liver. The N-terminal amino acid of the polypeptide chain was found to be blocked as that of spinach glycolate oxidase, contrastingly with that of rat kidney isozyme B. Its amino acid composition was comparable to that of other known L-2-hydroxyacid oxidases. Despite different substrate specificity, some immunological identity was observed between chicken liver L-2-hydroxyacid isozyme A and rat kidney isozyme B.

Alcohol Oxidoreductases↗
PubMed1990

Oxidation of the supplemental methionine source L-2-hydroxy-4-methylthiobutanoic acid by pure L-2-hydroxy acid oxidase from chicken liver.

The peroxisomal enzyme L-2-hydroxy acid oxidase A (EC 1.1.3.1) was isolated from chicken liver to better evaluate its part in the utilization of the L isomer of supplemental DL-hydroxy-4-methylthiobutanoic acid by birds fed diets containing the methionine hydroxy analogue. The 650-fold purified enzyme, a 169 kDa protein composed of four apparently identical subunits, exhibited a specific activity of 1.3 mumol glycolate oxidized.min-1.mg protein-1. Glycolate (Km = 0.10 mmol/L) was actually a better substrate than L-2-hydroxyisocaproate (Km = 0.63 mmol/L), L-2-hydroxy-4-methylthiobutanoate (Km = 1.73 mmol/L) and L-lactate (Km = 10.13 mmol/L). Under all substrate concentrations tested, the enzyme activity toward L-2-hydroxyisocaproate and L-2-hydroxy-4-methylthiobutanoate was 55 and 17%, respectively, of that toward glycolate. Although the highly purified enzyme was unable to oxidize D-lactate, D-methionine, L-methionine, L-mandelate and beta-phenyl-L-lactate, the latter two aromatic substrates were significantly oxidized by the first ammonium sulfate precipitate obtained during the isolation procedure, supposedly because of the presence of L-2-hydroxy acid oxidase isozyme B. Because the hepatic tissue concentration of glycolate, the physiological substrate for the enzyme, was rather low (10 mumol/L) as compared to the concentration of the methionine hydroxy analogue, one can expect that the conversion of L-2-hydroxy-4-methylthiobutanoate to 2-keto-4-methylthiobutanoate prior to L-methionine formation might proceed at a substantial rate in chickens fed the supplemental methionine source.

Alcohol Oxidoreductases↗
PubMed1990

Vancomycin-induced red man syndrome.

A total of 11 cases of red man syndrome collected among 650 children who had received vancomycin in our hospital between 1986 and 1988 (estimated prevalence 1.6%) were retrospectively analyzed. These 11 children were compared with 11 age-matched children who received vancomycin in whom red man syndrome did not develop. Of the patients with red man syndrome, 73%, and of the patients with no reaction, 45.4% received vancomycin for penicillin-resistant Staphylococcus epidermidis-positive cultures, or because of history of penicillin allergy. No difference was observed in the dose per kilogram given to both groups (12.9 +/- 3.5 mg/kg per dose in those with red man syndrome vs 12.3 +/- 6.9 mg/kg per dose in control children. The duration (mean +/- standard deviation) of vancomycin infusion was 45.9 +/- 16.7 minutes (range 10 to 90 minutes) in patients with red man syndrome and 54.5 +/- 7.6 minutes (range 45 to 65 minutes) in the control group (P = .07). In the 5 children with red man syndrome rechallenged with vancomycin, slower infusion rates prevented or reduced the syndrome, which emphasized the fact that the rate of administration is the important determinant of red man syndrome in susceptible cases. Clinically, the syndrome developed at the end of the infusion in most patients, but appeared as early as 15 minutes after initiation of the infusion. It was mostly manifested as a flushed, erythematous rash on the face, neck, and around the ears. Less frequently, the rash was distributed all over the body. Pruritus was usually localized to the upper trunk but was also generalized (2 of 11 children).(ABSTRACT TRUNCATED AT 250 WORDS)

Body Weight↗
PubMed1990

Low-income pregnant adolescents and their infants: dietary findings and health outcomes.

Dietary and other health-related data were obtained for 99 low-income, pregnant adolescents aged 13 to 19 years and their infants who were enrolled in the Teen Pregnancy Service (TPS). The dietetic services provided through TPS are highlighted for this sample of teens, 97% of whom were eligible for the WIC program. Average gestational age at time of enrollment for prenatal care was 18 weeks; 59% of the sample was anemic (hemoglobin value less than 120 gm/L). The average number of servings teens consumed each day from the four food groups was as follows: bread/grain, 5.0; milk, 2.8; meat, 2.8; and fruit/vegetable, 2.3. Teens who were overweight before pregnancy had heavier infants (mean = 3,344 gm) than their underweight peers (mean = 2,770 gm). Teens who gained 24 lb or less during pregnancy and who gave birth to full-term infants had infants with significantly lower birth weights (mean = 3,094 gm, p less than .008) than those who gained at least 25 lb (mean = 3,356 gm). Teens who smoked also had infants with lower birth weights than teens who did not smoke. Most teens bottle-fed their infants (82%). On the basis of our data, we conclude that low-income pregnant teens are likely to be at dietary risk. Dietary work with low-income pregnant adolescents is challenging and requires a thorough knowledge base about adolescent pregnancy, coupled with the ability to adapt traditional dietary counseling practices to meet the unique needs of these clients.

Adolescent↗
PubMed1989

Oxidation of methionine and 2-hydroxy 4-methylthiobutanoic acid stereoisomers in chicken tissues.

Oxidation of DL-2-hydroxy 4-methylthiobutanoic acid (DL-HMB), DL-methionine (DL-MET) and L-methionine (L-MET) in chicken tissue homogenates was compared using 1-14C-labelled tracers. The pattern of oxidation of the substrates was similar at both low (0.7 mM) and high (20 mM) concentrations. The rate of conversion to 2-keto 4-methylthiobutanoic acid (KMB) was highest for DL-MET and lowest for L-MET in kidney, liver and intestinal mucosa. In breast muscle, rates for DL-MET and L-MET were similar at 0.7 mM, but DL-HMB showed the highest rate at 20 mM. Kidney contained the highest specific activity for oxidation of all three substrates. Raising the pH of liver and kidney homogenates from 7.5 to 8.6 increased the oxidation of DL-MET, exclusively. Experiments with inhibitors of D-2-hydroxy acid dehydrogenase (EC 1.1.99.6) and L-2-hydroxy acid oxidase (EC 1.1.3.15) suggested that D- and L-HMB were stereospecifically oxidized by the enzymes. KMB stimulated L-MET oxidation in kidney yet inhibited L-MET oxidation in liver homogenates. The effect of KMB on DL-MET and DL-HMB oxidation also varied between tissues. Amino-oxyacetate inhibited L-MET oxidation completely and DL-MET and DL-HMB oxidation almost completely in both kidney and liver. L-Cycloserine was less potent than amino-oxyacetate and decreased L-MET oxidation more in kidney than in liver. It can be calculated from the results that, at low substrate concentrations, the liver contributes principally to the whole body oxidation of both DL-HMB and DL-MET. At high (greater than physiological) concentrations, DL-HMB would be oxidized principally in skeletal muscle. At all concentrations, L-MET would be converted to KMB mainly in the muscle.

Animal Nutritional Physiological Phenomena↗
PubMed1986

Anaphylactoid and systemic reactions following saline enema administration. Six case reports.

This report describes six children with spina bifida who have experienced a total of 13 episodes of generalized hives, angioedema and in two cases, anaphylactoid reactions immediately following saline enema infusions. The enemas were administered using a kit comprised of a plastic bag, tubing, and rectal end-piece. The reactions always occurred with the first use of new kits. A third child developed a systemic reaction with only the rectal end-piece in situ and without infusion of fluid. An in-hospital challenge using a new end-piece in one patient, who was clinically the most sensitive, produced an acute anaphylactoid reaction implicating the end-piece as the most likely source of the problem. The definitive mechanism(s) of the reactions and the agent(s) responsible for them presently remain unknown.

Anaphylaxis↗
PubMedDate not supplied

Comparative oxidative rates of methionine hydroxy analogue in rat and chicken kidney.

1. L-2-HAOX A and L-2-HAOX B were purified from chicken and rat kidney with purification factors of 550 and 45, respectively. 2. It was established that both enzymes were tetrameric (M(r) = 169,000) and consisted of 40 kDa monomers. 3. While chicken kidney L-2-HAOX A is N-terminally blocked like spinach glycolate oxidase and chicken liver L-2-HAOX A, L-2-HOAX B begins with a Pro residue. 4. The kinetic parameters of L-HMB oxidation by L-2-HAOX A and B were determined. 5. The results are particularly interesting as regards L-HMB oxidation by L-2-HAOX B.

Alcohol Oxidoreductases↗
PubMedDate not supplied

Peer discussions of cancer among Hispanic migrant farm workers.

Hispanic migrant agricultural workers' exposure to pesticides and other agrichemicals places them at increased risk for a variety of acute and chronic conditions, including cancer. As a socioeconomically disadvantaged group, migrant workers also face many barriers to effective cancer control. In 1992, a series of focus groups was held with 55 Hispanic migrant agricultural workers (22 women, 33 men) in central Wisconsin to gather information on their knowledge and attitudes regarding cancer etiology and treatment, their practices regarding cancer screening and early detection, and their concerns regarding occupational exposure to pesticides. Beliefs that pesticides are toxic and can cause health problems were common among participants. In addition, however, participants reported that they are reluctant to demand occupational protections to which they are entitled because they are afraid of losing their jobs. Study results also suggest that barriers to effective primary and secondary prevention of cancer in this Hispanic migrant agricultural worker population include knowledge and information barriers, cultural barriers, and socioeconomic barriers. A lack of knowledge and information regarding the causes of cancer, its prevention, and its early detection and treatment was evident among participants, which in turn was reflected in strong fatalistic attitudes toward the disease. Cultural barriers included attitudes of embarrassment and shame associated with physical examinations and women's strong discomfort with male clinicians. Socioeconomic barriers to secondary prevention included the cost of obtaining health services, time constraints associated with the need to work and long working days, and a lack of transportation. Efforts to improve cancer screening as well as other preventive health services in the Hispanic migrant agricultural worker population must acknowledge these barriers and address as many of them as possible to be successful.

Agriculture↗