PubMed Health⌕ Search

Biomedical subjects

J Gagnon

Publications and source records attributed to J Gagnon.

At least 91 records · Page 5Linked to original sources
PubMed1999

A mitochondrial DNA D-loop polymorphism and obesity in three cohorts of women.

OBJECTIVE: To examine the hypothesis of an association between a mtDNA D-loop Kpn I restriction site polymorphism (RSP) at base pair (bp) 16,133 (morph-1) and obesity in women. DESIGN: Comparisons of carriers and noncarriers of the mutation for BMI (Body Mass Index) levels and of the frequency of the mutation in obese and normal weight women. SUBJECTS: 567 unrelated adult Caucasian non-diabetic women from the HERITAGE Family Study (n = 63; BMI: 15-47 kg/m2), Quebec Family Study (QFS; 77 controls, BMI: 19-26 kg/m2 and 38 obese, BMI: 27-56 kg/m2) and Swedish Obese Subjects (SOS) Study (81 controls, BMI: 18-26 kg/m2 and 308 obese, BMI: 33-58 kg/m2). MEASUREMENTS: BMI was calculated from weight and height (kg/m2). mtDNA was amplified between base pair 15,928 and 16,500 by polymerase chain reaction (PCR) and digested with the restriction endonuclease Kpn I. RESULTS: No significant differences in the age-adjusted BMI for the mtDNA D-loop Kpn I RSP at base pair (bp) 16,133 (morph-1) between carriers and non-carriers in the HERITAGE cohort. No significant association was found between BMI and the Kpn I RSP carrier status in the SOS and QFS cohorts. The observed frequencies for the Kpn I RSP were not significantly (P > 0.05) different between the SOS controls and SOS obese irrespective of the degree of severity of obesity (BMI > 40, > 45 or > 50 kg/m2). CONCLUSION: We conclude that the mtDNA D-loop Kpn I RSP at bp 16,133 (morph-1) is not a determinant of human obesity.

Adult↗
PubMed1999

Association and linkage between an insulin-like growth factor-1 gene polymorphism and fat free mass in the HERITAGE Family Study.

OBJECTIVE: To investigate the relationship between a DNA microsatellite marker in the insulin-like growth factor-1 (IGF-1) gene and body composition phenotypes before and following exposure to 20 weeks of aerobic exercise training in the HERITAGE Family Study. DESIGN: A controlled intervention study: fat mass (FM), percentage body fat (%FAT), fat free mass (FFM), body mass index (BMI) and abdominal visceral fat (AVF) at baseline (B) and in response to training (delta=post minus pre-training value) were measured. Association and sib-pair linkage studies were undertaken. SUBJECTS: A maximum of 502 Caucasian individuals (99 families; 190 parents and 312 adult offspring). MEASUREMENTS: The polymorphism was typed by polymerase chain reaction and DNA sequencer. The body composition phenotypes were determined from the underwater weighing method, and AVF was assessed by computerized tomography scan. RESULTS: 11 alleles were found: the lengths ranged from 189 to 209 base pairs (bp), and the frequency of the most common allele, 189 bp, reached 0.71. In association studies, significant differences for B-FM, B-FFM and B-%FAT among the three genotypes (189 bp homozygotes, heterozygotes and non-carriers) were detected. The B-FM for 189 bp homozygotes was 19.7+/-0.6 kg, but 21.6+/-0.7 and 21.3+/-1.5 kg for the 189 bp heterozygotes and the non-189 bp carriers respectively (P=0.03 after adjustment for age, sex and generation). Differences among the three genotypes were also observed for B-%FAT (25.9+/-0.5 versus 27.4+/-0.6 and 26.6+/-1.2 kg; P<0.05) and B-FFM (53.7+/-0.4 versus 54.9+/-0.5 kg and 54.4+/-1.0 kg; P<0.05). No significant difference for B-AVF was found among the three genotypes. Following 20 weeks of endurance exercise, the 189 bp homozygotes gained only about half the amount of FFM compared with the other two IGF-1 genotypes (0.3+/-0.1 vs 0.7+/-0.1 and 0.5+/-0.2 kg; P=0.005). A strong linkage was observed between the IGF-1 marker and the changes in FFM (308 pairs of full sibs, P=0.0002) but only a suggestive linkage with B-AVF (352 pairs of full sibs, P<0.02) CONCLUSION: Associations were detected between the IGF-1 gene marker and FM, %FAT and FFM at baseline, and a strong association with the changes in FFM in response to training. Moreover, the IGF-1 gene marker was found to be strongly linked to the changes in FFM in response to 20 weeks of endurance exercise and weakly linked to abdominal visceral fat in the sedentary state.

Adolescent↗
PubMed1999

Unfolding studies of human adenovirus type 2 fibre trimers. Evidence for a stable domain.

Adenovirus fibres are trimeric proteins that protrude from the 12 fivefold vertices of the virion and are the cell attachment organelle of the virus. They consist of three segments: an N-terminal tail, which is noncovalently attached to the penton base, a thin shaft carrying 15 amino acid pseudo repeats, and a C-terminal globular head (or knob) which recognizes the primary cell receptor. Due to their exceptional stability, which allows easy distinction of native trimers from unfolded forms and folding intermediates, adenovirus fibres are a very good model system for studying folding in vivo and in vitro. To understand the folding and stability of the trimeric fibres, the unfolding pathway of adenovirus 2 fibres induced by SDS and temperature has been investigated. Unfolding starts from the N-terminus and a stable intermediate accumulates that has the C-terminal head and part of the shaft structure (shown by electron microscopy). The unfolded part can be digested away using limited proteolysis, and the precise digestion sites have been determined. The remaining structured fragment is recognized by monoclonal antibodies that are specific for the trimeric globular head and therefore retains a native trimeric structure. Taken together, our results indicate that adenovirus fibres carry a stable C-terminal domain, consisting of the knob with five shaft-repeats.

Amino Acid Sequence↗
PubMed1999

Isolation, amino acid sequence and functional assays of SGTx1. The first toxin purified from the venom of the spider scodra griseipes.

A new toxin (SGTx1) was purified from the venom of the spider Scodra griseipes by a combination of gel filtration and reverse-phase chromatography. The complete amino acid sequence of SGTx1, TCRYLFGGCKTTADCCKHLACRSDGKYCAWDGTF, was established by direct automated Edman degradation, and is in perfect agreement with the molecular mass of 3775 Da found by mass spectrometry. The primary structure of SGTx1 exhibited sequence identity with other spider toxins such as hanatoxin (76%), TxP5 toxin (32%) and huwentoxin (26%). The six cysteines in the sequence suggested three disulfide bridges, the presence of which was demonstrated by mass spectrometry after dithiothreitol reduction. Analysis of secondary structure using circular dichroism spectrometry yielded more than 50% beta-sheet and about 15-20% beta-turn. The extent of the beta-content and the presence of disulfide bridges suggest a structure of interconnected beta-strands. In addition, a study of membrane/toxin interactions was carried out by reconstitution in planar lipid bilayers and by antibacterial assays. SGTx1 displays moderate pore-forming ability (conductance of about 100 pS in 1 M NaCl), but antibacterial activity was not observed against Gram-positive or Gram-negative strains. As a preliminary assay, the activity of SGTx1 was investigating using electrophysiological measurements. At 0.15 microM, SGTx1 reversibly inhibits more than 40% of outward potassium currents in rat cerebellum granular cells. This result is reminiscent with the effect described for hanatoxin extracted from the venom of Grammostola spatulata.

Amino Acid Sequence↗
PubMed1999

Alterations in body weight and composition consequent to 20 wk of endurance training: the HERITAGE Family Study.

BACKGROUND: Obesity is a major public health problem in the United States. The role of physical activity and formal exercise in controlling body weight has not been clearly determined. OBJECTIVE: This study determined the magnitude of change in body weight and composition across sex, race, and age in response to 20 wk of endurance training. DESIGN: Men and women (n = 557) of various ages (16-65 y) and 2 races (black and white) exercised on cycle ergometers 3 d/wk for a total of 60 exercise sessions starting at 55% of maximal oxygen consumption (VO(2)max) for 30 min/session and building to 75% of VO(2)max for 50 min/session, where it was maintained during the last 6 wk. Skinfold-thickness measurements, circumferences, body composition (by hydrostatic weighing), and body fat distribution (by computed tomography scan at L4-L5 and the waist-hip ratio) were determined before and after training. RESULTS: All skinfold-thickness and circumference measures, waist-hip ratio, body mass index, total body mass, fat mass, percentage body fat, and computed tomography scan measures of total, subcutaneous, and visceral abdominal fat decreased with training, whereas total body density and fat-free mass increased. These changes were significant, but small. There were several differences in training response by sex and race, but not by age. CONCLUSIONS: A short-term exercise intervention can induce favorable changes in body composition, but the magnitude of these changes is of limited biological significance. Increasing physical activity likely has a major effect on body-composition and fat distribution characteristics only when it is of a greater magnitude and sustained for much longer periods

Adolescent↗
PubMed1999

Accuracy of prediction equations to estimate submaximal VO2 during cycle ergometry: the HERITAGE Family Study.

UNLABELLED: It was hypothesized that more accurate equations for estimating submaximal VO2 during cycle ergometry could be developed if more independent variables were used in the equation. PURPOSE: The purposes of this study were: (1) to develop new equations for estimating submaximal VO2 during cycle ergometry; and (2) to examine the accuracy of the newly developed equations and those of the American College of Sports Medicine (1995), Berry et al. (1993), Lang et al. (1992), Latin and Berg (1994), and Londeree et al. (1997). METHODS: Subjects (715 men and women, ages 16-65 yr, from the HERITAGE Family Study) completed a maximal cycle ergometry test, two submaximal trials at 50 W and 60% of VO2max, hydrostatic weighing, and stature and body mass measures before and after 20 wk of cycle ergometry training. Regression analysis generated prediction equations using pretraining data from the 60% trials. RESULTS: No equation with more independent variables was better than an equation that used only power output. This equation, HERITAGE-1, with only power output was cross-validated using the "jackknife" technique. Paired t-tests, mean differences, SEEs, and Es were used to compare the VO2 estimated by HERITAGE-1 and those of previously published equations with the measured VO2 at 60% of VO2max. CONCLUSIONS: HERITAGE-1 was slightly better than the equations of ACSM, Lang et al., and Latin and Berg using pretraining data but was not better when using post-training data. All four of these equations were superior to the equations of Berry et al. and Londeree et al.

Adolescent↗
PubMed1999

Linkage between a muscle-specific CK gene marker and VO2max in the HERITAGE Family Study.

PURPOSE: We have reported a significant association between VO2max in the sedentary state and its response (delta VO2max) to an endurance training program with a muscle-specific creatine kinase (CKMM) gene polymorphism. The purpose of this study was to test the hypothesis of genetic linkage between the same CKMM marker and VO2max in the sedentary state as well as delta VO2max. METHODS: Sib-pair linkage analysis was performed on 277 full sib-pairs from 98 Caucasian nuclear families of the HERITAGE Family Study. VO2max was measured during cycle ergometry tests before and after 20 wk of endurance training. The CKMM polymorphism was detected by the polymerase chain reaction and digestion with the Ncol restriction enzyme. RESULTS: Frequencies for the rare (1170 base pairs) and common (985 + 185 base pairs) alleles were 0.32 and 0.68, respectively. No significant linkage (t = -0.02, P = 0.49) was detected between the CKMM marker and the age and sex adjusted VO2max (mL x kg(-1) x min(-1)) in the sedentary state. However, after adjustment of delta VO2max for the effects of age, sex, initial VO2max, and body mass, evidence for linkage between the CKMM locus and delta VO2max was suggestive (P = 0.04). CONCLUSION: The present results provide further support for the notion that the CKMM gene, or some gene in close linkage disequilibrium with it, may contribute to individual differences in the VO2max response to endurance training.

Adolescent↗
PubMed1999

Reproducibility of maximal exercise test data in the HERITAGE family study.

PURPOSE: The reproducibility of responses to maximal cycle ergometer testing was determined using data from the HERITAGE Family study at four Clinical Centers in the United States and Canada. METHODS: Reproducibility was determined from maximal exercise test data obtained a) on 2 d in a sample of 390 subjects (198 men and 192 women), b) across 4 d in an Intracenter Quality Control (ICQC) substudy with 55 subjects who were not part of the main study, and c) across 2 wk in a Traveling Crew Quality Control (TCQC) substudy with the same eight subjects who were tested at each of the four centers. Reproducibility was evaluated using technical errors, coefficients of variation (CV) for repeated measures, and intraclass correlation coefficients (ICC) for selected variables obtained on the main cohort, as well as on the ICQC and TCQC substudies. RESULTS: With the exception of systolic and diastolic blood pressures and respiratory exchange ratio, all the other variables (heart rate, ventilation, VO2, and VCO2) were highly reproducible, with CV below 10% and ICC over 0.86. These results were similar to those previously reported on the same subjects at a submaximal power output associated with 60% VO2max. Results were consistent for the main cohort, the ICQC sample, the TCQC sample, and across all four Clinical Centers. CONCLUSIONS: Day-to-day variations are small and reproducibility is high for maximal values of heart rate, ventilation, VO2 and VCO2 at each of the four Clinical Centers of the HERITAGE Family Study.

Adolescent↗
PubMed1999

Familial aggregation of VO(2max) response to exercise training: results from the HERITAGE Family Study.

The aim of this study was to test the hypothesis that individual differences in the response of maximal O(2) uptake (VO(2max)) to a standardized training program are characterized by familial aggregation. A total of 481 sedentary adult Caucasians from 98 two-generation families was exercise trained for 20 wk and was tested for VO(2max) on a cycle ergometer twice before and twice after the training program. The mean increase in VO(2max) reached approximately 400 ml/min, but there was considerable heterogeneity in responsiveness, with some individuals experiencing little or no gain, whereas others gained >1.0 l/min. An ANOVA revealed that there was 2.5 times more variance between families than within families in the VO(2max) response variance. With the use of a model-fitting procedure, the most parsimonious models yielded a maximal heritability estimate of 47% for the VO(2max) response, which was adjusted for age and sex with a maternal transmission of 28% in one of the models. We conclude that the trainability of VO(2max) is highly familial and includes a significant genetic component.

Adolescent↗
PubMed1998

Purification, molecular characterization and catalytic properties of a Pseudomonas fluorescens enzyme having cholinesterase-like activity.

An enzyme with a cholinesterase (ChE) activity, produced by Pseudomonas fluorescens, was purified to homogeneity in a three-step procedure. Analysis by non-denaturing and SDS-PAGE, and by isoelectric focusing, indicated that the enzyme was a monomer of 43 kDa, with a pI of 6.1. The N-terminal sequence, AEPLKAVGAGEGQLDIVAWPGYIEA, showed some similarities with proteins of the ChE family and a strong similarity with a protein from Escherichia coli with unknown structure and function. Cholinesterase activity at pH 7.0 and 25 degreesC was maximum with propionylthiocholine as substrate (kcat,app=670 min-1), followed by acetylthiocholine, and significantly lower with butyrylthiocholine. Catalytic specificity (kcat/Km) was the same for propionylthiocholine and acetylthiocholine, but was two orders of magnitude lower for butyrylthiocholine. Kinetics of thiocholine ester hydrolysis showed inhibition by excess substrate which was ascribed to binding of a second substrate molecule, leading to non-productive ternary complex (Km=35 microM, KSS=0.49 mM with propionylthiocholine). There was low or no reactivity with organophosphates and carbamates. The enzyme inhibited by echothiophate (kII=0.44x102 M-1 min-1) was not reactivated by pralidoxime methiodide. However, the P. fluorescens enzyme had affinity for procainamide and decamethonium, two reversible ChE inhibitors used as affinity chromatography ligand and eluant, respectively. Although similarity of the N-terminal amino acid sequence of the enzyme with an internal sequence of ChEs is weak, its catalytic activity towards thiocholine esters, and its affinity for positively charged ligands supports the contention that this enzyme may belong to the ChE family. However, we cannot rule out that the enzyme belongs to another structural family of proteins having cholinesterase-like properties. The reaction of the enzyme with organophosphates suggests that it is a serine esterase, and currently this enzyme may be termed as having a cholinesterase-like activity.

Amino Acid Sequence↗
PubMed1998

Kinetic and mass spectrometric analyses of the interactions between plant acetohydroxy acid isomeroreductase and thiadiazole derivatives.

Plant acetohydroxy acid isomeroreductase (EC 1.1.1.86), the second enzyme of the branched chain amino acid biosynthetic pathway, has been submitted to high-throughput screening for herbicide discovery. We report here the discovery of a new class of compounds belonging to the thiadiazole family, which exhibit a strong inhibitory effect on this plant enzyme. Kinetic analyses revealed that these compounds act as either reversible or irreversible noncompetitive inhibitors of the plant enzyme. Reversibility or irreversibility of these compounds can be attributed to the nature of the additional groups of the thiadiazole ring favoring or not favoring the formation of a covalent adduct. Mass spectrometric experiments on the complex between an irreversible compound belonging to the thiadiazole family and the plant enzyme identified Cys498 as the binding site of the inhibitor.

Alcohol Oxidoreductases↗
PubMed1998

The nuclear RPL4 gene encodes a chloroplast protein that co-purifies with the T7-like transcription complex as well as plastid ribosomes.

We have cloned and sequenced the cDNA and the gene coding for plastid ribosomal protein L4 (RPL4) from two higher plant species, spinach and Arabidopsis thaliana. Ribosomal protein L4 is one of the ribosomal proteins for which extraribosomal functions in transcriptional regulation has been demonstrated in prokaryotes. Sequence comparison of the two plant cDNAs and genes shows that the RPL4 gene has acquired a remarkable 3' extension during evolutionary transfer to the nuclear genome. This extension harbors an intron and codes for a glutamic and aspartic acid-rich amino acid sequence that resembles highly acidic C-terminal tails of some transcription factors. Co-purification of ribosomal protein L4 with plastid RNA polymerase and transcription factor CDF2 using different purification protocols as well as the surprising amino acid sequence of the L4 protein make it a likely candidate to play a role in plastid transcriptional regulation.

Amino Acid Sequence↗
PubMed1998

Polypeptide:N-acetylgalactosaminyltransferase activities towards the mucin MUC5AC peptide motif using microsomal preparations of normal and tumoral digestive mucosa.

The selected-acceptor substrate peptide (TTSAPTTS), deduced from the human mucin gene MUC5AC (expressed essentially in the human gastric and tracheobronchial mucosa), was used to assay polypeptide:N-acetylgalactosaminyltransferases (GalNAc transferases) of different microsomal preparations, obtained from gastric and colonic mucosa in normal and tumoral situations. The O-glycosylated products, analyzed by capillary electrophoresis and electrospray mass spectrometry, showed a variable number of GalNAc O-linked to the different hydroxy amino acids of TTSAPTTS, depending on the tissue studied. Our observations were consistent with the existence of more than one form of GalNAc transferases which were expressed differentially in the gastrointestinal tract (stomach and/or colon). The levels of enzyme activities showed a tissue-specific pattern as they were high in normal colonic tissue and low in colon cancer. On the other hand, in the tumoral gastric tissue (displaying intestinal metaplasia) a high level of GalNAc transferase activities was obtained, similar to that found in the normal colon. Moreover, slight discrepancies (activities and number of O-linked GalNAc) were only detected between normal gastric and tumoral colonic preparations. Thus, the data indicated that the dedifferentiation of the gastric cancer tissue may induce GalNAc transferase activities similar to those in the normal colonic, tissue and that colonic and gastric tissues may contain families of glycosyltransferases involved specifically in reaction towards particular peptide or protein substrates. In addition, the analysis by capillary electrophoresis and electrospray mass spectrometry revealed, in tumoral gastric as well as in normal colonic tissues, a high dipeptidylaminotransferase activity inducing an elongation of TTSAPTTS by dithreonine. This activity was low in normal gastric and tumoral colonic tissues.

Animals↗
PubMed1998

The protein sequence of an archaeal catalase-peroxidase.

The gene encoding a catalase-peroxidase of archaeal origin, the halophilic catalase-peroxidase from Haloarcula marismortui, was sequenced. The primary structure proposed was confirmed by Edman degradation and mass spectrometry analyses of proteolytic fragments of the purified protein. The open reading frame in the gene corresponds to 731 amino acids and the calculated mass of the mature protein (deleted of the N-terminal methionine) is 81,253.65 Da, in reasonable agreement with the value of 81,292 +/- 9 Da previously measured by mass spectrometry. Southern and Northern blot analyses showed that the protein is encoded by a single gene as a monocistronic transcript. The protein sequence shows a high level of identity with bacterial catalase-peroxidases, with strongly conserved regions around the heme binding histidines. Similarly to other soluble halophilic proteins, it shows the excess of acidic residues that has been associated with solvation in halophilic adaptation.

Amino Acid Sequence↗
PubMed1998

Influence of the amino acid sequence on the MUC5AC motif peptide O-glycosylation by human gastric UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferase(s).

The present work was carried out to study the role of the peptide moiety in the addition of O-linked N-acetylgalactosamineto human apomucin using human crude microsomal homogenates from gastric mucosa (as enzyme source) and a series of peptide acceptors representative of tandem repeat domains deduced from the MUC5AC mucin gene (expressed in the gastric mucosa). Being rich in threonine and serine placed in clusters, these peptides provided several potential sites for O-glycosylation. The glycosylated products were analysed by a combination of electrospray mass spectrometry and capillary electrophoresis in order to isolate the glycopeptides and to determine their sequence by Edman degradation. The O-glycosylation of our MUC5AC motif peptides gave information on the specificity and activity of the gastric microsomal UDP-N-acetylgalactosamine:polypeptide N-acetylgalactosaminyltransferase(s). The proline residues and the induced-conformations are of great importance for the recognition of MUC5AC peptides but they are not the only factors for the choice of the O-glycosylation sites. Moreover, for the di-glycosylated peptides, the flanking regions of the proline residues strongly influence the site of the second O-glycosylation.

Amino Acid Sequence↗
PubMed1998

DNA polymorphism in the uncoupling protein 1 (UCP1) gene has no effect on obesity related phenotypes in the Swedish Obese Subjects cohorts.

OBJECTIVE: To investigate the relationships between the A-G point mutation at position -3826 bp in the 5' flanking domain of the uncoupling protein 1 (UCP1 A-3826G) and some obesity phenotypes in the Swedish Obese Subjects (SOS) cohorts of obese and non-obese men and women. Previous studies have supported the hypothesis of an association between the UCP1 A-3826G polymorphism and body weight regulation in humans. DESIGN: Case-control study comparing obese subjects from the SOS registry and a sample of the Swedish general population (body mass index (BMI) <27 kg/m2) with respect to genotype and allele frequencies of the UCP1 A-3826G polymorphism. SUBJECTS: A total of 985 Swedish subjects including 674 obese (310 Male; 364 Female) and 311 non-obese subjects (54 Male; 257 Female) from the SOS cohorts. MEASUREMENTS: DNA was extracted from total blood and genotyped by PCR-RFLP. Obesity-related phenotypes include weight history for SOS obese cohort and current weight, BMI, waist circumference and waist to hip ratio (WHR) for obese and normal weight subjects. RESULTS: No significant difference in the allelic frequencies between obese and non-obese subjects (0.25 vs 0.24; P = 0.67). In both genders, current weight, BMI, waist circumference, WHR and weight gain over time (either measures of maximal weight ever achieved minus weight at 20 y or current weight minus weight at 20 y) were similar in carriers and non-carriers of the UCP1 A-3826G mutation (P>0.05). Similar results were obtained when the three genotypes were compared. CONCLUSIONS: In contrast to what was found in other populations, the UCP1 A-3826G sequence variation is not associated with obesity-related phenotypes and weight gain over time in subjects from the SOS cohorts.

Adult↗