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Biomedical subjects

C Michaud

Publications and source records attributed to C Michaud.

At least 19 recordsLinked to original sources
PubMed1998

Knowledge and participation of general practitioners in cervical cancer screening: survey in a French pilot area.

BACKGROUND: Eighteen months after the beginning of a pilot cervical cancer screening program in a French district of 484,770 inhabitants, a survey was performed among general practitioners (GP). The aim was to assess their knowledge of the screening policy, the factors related to their participation, the difficulties they encounter and their training needs. METHODS: A random sample of 168 GPs was taken from a medical association file. Eighty-seven percent of the physicians agreed to be interviewed by phone. The questionnaire was standardized and made up of open questions. RESULTS: On the whole, screening policy was not well known to the GPs: 58 percent believed screening had to begin before age 21 and could be discontinued before age 61. Sixty percent of GPs declared that they provided women with written information, and 49 percent that they offered Pap smears to all women. Seventy-nine percent said that they took Pap smears, but 39 percent claimed they had difficulty mainly due to women's reluctance or to technical problems. Few GPs expressed training needs. Reported difficulties and expressed need for training increased with the physician's age. GP concern for public health activities increased their participation in the campaign. CONCLUSION: Pilot programs have to implement measures which can help GPs to deal with community care and screening activities since GP involvement is one of the essential conditions of successful organized screening.

Adult↗
PubMed1998

[Food habits, consumption, and knowledge of a low-income French population].

Behaviors related to nutrition as well as the eating habits of low-income French people are analyzed from data collected by the Nutrition and Health Barometer of the CFES in 1996. French people with monthly incomes of less than 4000 francs appear to go to fast-food restaurants more often than to other types of restaurant (for leisure or work). They appear to eat their three main meals alone more often, to spend less time over the evening meal, to watch television during their noon and evening meals, to have cheese or another dairy product rather than a main dish, and to limit their evening meal to a single dish. They are less numerous than higher-income people to have the "ideal" breakfast. These economically disavantaged French people do their shopping more often in large of medium-sized supermarkets and more often plan their meals according to the family budget. In terms of food they are more numerous to eat neither fruit nor vegetables; they consume less pork, fish and shellfish, dairy products, alcoholic beverages and especially before-dinner drinks. This study shows that the eating behavior of low-income French people is less in conformity with commonly accepted nutritional recommendations. Likewise, the rate of obesity observed among the women from this households appears high.

Adolescent↗
PubMed1997

[School lunch and nutrition of pupils ended in disadvantaged environments: reports, stakes, assistance with the decision].

Because of a growing poverty in France, the most disadvantaged families are having to give up school lunches for their children, with negative consequences from the point of view of nutrition. The data collected and worked by the authors calls for a more qualified interpretation. A drop in school meal attendance is a reality in some establishments and in some departments. Falling incomes in families experiencing the greatest difficulties undoubtedly influence the choice of expenditure, but it is not possible to generalise it at national level or to confirm any downward trend in attendance. Beside socio-economic factors, it is wide to consider also the food supply, school catering conditions and others factors bound up with changes in eating habits among young and their families. In any case, there is no proof for the moment of any repercussions on pupil's nutritional health, even though this will have to be structurally monitored. Neither has it been proved that pupils who do not take school meals are any the less well fed.

Food Services↗
PubMed1996

Calcification in colorectal hepatic metastases correlates with longer survival.

BACKGROUND: Calcification occurs in 12-27% of hepatic colorectal metastases, but its clinical significance and its influence on prognosis are unknown. METHODS: All patients diagnosed with colorectal liver metastases at the Ottawa Regional Cancer Center in 1991 (n = 97), as well as those enrolled in chemotherapy trials in 1990-1992 (n = 51), were entered into a retrospective cohort study. Thirty-six patients were excluded due to inadequate follow-up. In the remaining 112, abdominal CT scans and/or ultrasound examinations were used to determine the presence of calcification. Charts were reviewed for variables, including primary tumour pathology, amount of liver involvement by tumour (< 25%, 25-50%, > 50%), and the chemotherapeutic agents received, and were subjected to multivariate and regression analysis. End point was survival in months or to December 1993 (median follow up 24 months). RESULTS: Patients with calcification (n = 31) (28%) were compared to those who did not have calcifications (n = 81). The groups were comparable with respect to sex, age, time to calcification, time to metastases, and treatment type. Calcification occurred independent of the degree of tumour differentiation, the presence of mucinous adenocarcinoma, or the hepatic tumour burden. Nine patients with calcified metastases (30%) had calcification at presentation. Biopsies showed calcification next to viable tumour cells with an absence of an inflammatory reaction. Survival was improved with better primary tumour differentiation and less tumour burden. The presence of calcification had a statistically highly significant improvement in survival (P < 10(-6), relative risk = .19) independent of other variables. CONCLUSIONS: The presence of calcification within a colorectal liver metastasis appears to imply a significantly better prognosis.

Aged↗
PubMed1996

Reconstitution of ionic channels from inner and outer membranes of mammalian cardiac nuclei.

Recent reports suggest that the nuclear envelope possesses specific ion transport mechanisms that regulate the electrolyte concentrations within the nucleoplasm and perinuclear space. In this work, intact nuclei were isolated from sheep cardiac cells. After chromatin digestion, the nuclear envelopes were sonicated and four nuclear vesicle populations were separated by sucrose step gradients (SF1-SF4). These fractions were compared by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and their protein content was analyzed by Western blot, using lamin and SEC 61 antibodies. The lamins, which are associated with the inner nuclear membrane, were present in three fractions, SF2, SF3, and SF4, with a lower amount in SF2. The SEC 61 protein, a marker of the rough endoplasmic reticulum, was detected in small amounts in SF1 and SF2. Upon fusion of vesicles into bilayers, the activities of nuclear ionic channels were recorded in 50 mM trans/250 mM cis KCl or CsCl, pH 7.2. Two types of Cl- selective channels were recorded: a large conducting 150-180-pS channel displaying substates, and a low conducting channel of 30 pS. They were both spontaneously active into bilayers, and their open probability was poorly voltage dependent at negative voltages. Retinoic acid (10(-8) M) increases the po of the large Cl- conducting channel, whereas ATP modifies the kinetics of the low conductance anion selective channel. Our data also suggest that this anionic channel is mainly present in the SF3 and SF4 population. The presence of a 181 +/- 10 pS cation-selective channel was consistently observed in the SF2 population. The behavior of this channel was voltage dependent in the voltage range -80 to +60 mV. Furthermore, we report for the first time the activity of a channel exclusively present in the SF3 and SF4 fractions, shown to contain mainly inner membrane vesicles. This cation selective channel displays a 75-pS conductance in 50 mM trans/250 mM cis K-gluconate. It is concluded that the bilayer reconstitution technique is an attractive approach to studying the electrophysiological properties of the inner and outer membranes of the nuclear envelope.

Animals↗
PubMed1994

Inhibition of the proteolytic activity of the multicatalytic proteinase complex (proteasome) by substrate-related peptidyl aldehydes.

Evidence indicates that a component of the multicatalytic proteinase complex (MPC) that preferentially cleaves bonds after branched chain amino acids (BrAAP) is a major factor responsible for the protein-degrading activity of the MPC. We report here the synthesis of substrate-related peptidyl aldehydes that inhibit the activity of this component toward both synthetic peptide substrates and proteins. The most potent of the inhibitors, Cbz-Gly-Pro-Phe-leucinal (Cbz-GPFL-CHO) inhibits competitively with a Ki of 1.5 microM. The peptidyl aldehydes also inhibit the small neutral amino acid preferring and the peptidylglutamyl-peptide hydrolyzing activities of the MPC. The chymotrypsin-like activity is only weakly inhibited, and the trypsin-like activity is moderately activated. The importance of a Pro residue in the P3 position and a leucinal residue in the P1 position for inhibition of the BrAAP component is indicated by the finding that replacement of these residues by a glycine or phenylalaninal, respectively, markedly increases the Ki. Cbz-GPFL-CHO inhibited the BrAAP activity with the same Ki both before and after activation of this component by exposure of the MPC to 3,4-dichloroisocoumarin, suggesting that the peptidyl aldehyde is an effective inhibitor of both the overt and latent proteolytic activities of the MPC. Incubation of a human breast cancer cell line (MCF-7) in culture with the inhibitors of the BrAAP component led to an accumulation of ubiquitin-protein conjugates, indicating inhibition of the ubiquitin-dependent proteolytic pathway.

Aldehydes↗
PubMed1994

Evidence that the nature of amino acid residues in the P3 position directs substrates to distinct catalytic sites of the pituitary multicatalytic proteinase complex (proteasome).

Cleavage of bonds after neutral amino acids by the multicatalytic proteinase complex (MPC) has been recently shown to be catalyzed by at least three distinct components [Orlowski, M., Cardozo, C., & Michaud, C. (1993) Biochemistry 32, 1563-1572]. One component, designated as chymotrypsin-like (ChT-L), cleaves peptide bonds on the carboxyl side of hydrophobic residues and is also active toward peptidyl-arylamide bonds. A second component, designated as branched-chain amino acid preferring (BrAAP), and a third component, designated as small neutral amino acid preferring (SNAAP), cleave preferentially bonds on the carboxyl side of branched-chain amino acids and between small neutral amino acids, respectively. Evidence indicates that the BrAAP component is a major factor responsible for degradation of protein by the MPC. The purpose of the present study was to identify the structural requirements that determine the involvement of these components in cleavage of peptides after different neutral amino acids. A series of substrates was synthesized with the aim of probing the role of residues beyond those flanking the scissile bond in directing substrates to defined catalytic sites. The data indicate that a proline or glycine residue in the P3 position directs the substrate to the catalytic site of the BrAAP component provided that a branched-chain amino acid is present in the P1 position. A proline residue in P3 is also important for involvement of the SNAAP component in substrate degradation. The presence of this residue interferes with substrate binding to the catalytic site of the ChT-L activity, even in the presence of a phenylalanine residue in the P1 position.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1994

External assistance to the health sector in developing countries: a detailed analysis, 1972-90.

This study, which was conducted for the World Bank's World development report 1993: investing in health, provides an objective analysis of the external assistance to the health sector by quantifying in detail the sources and recipients of such assistance in 1990, by analysing time trends for external assistance to the health sector over the last two decades, and, to the extent possible, by describing the allocation of resources to specific activities in the health sector. The main findings of the study are that total external assistance to the health sector in 1990 was US$ 4800 million, or only 2.9% of total health expenditures in developing countries. After stagnation in real terms during the first half of the 1980s, health sector assistance has been increasing since 1986. Despite their small volume, external assistance at the margins may play a critical role in capital investment, research and strategic planning. The study confirms prior findings that health status variables per se are not related to the amount of aid received. Comparing investments to the burden of disease shows tremendous differences in the funding for different health problems. A number of conditions are comparatively under-financed, particularly noncommunicable diseases and injuries.

Communicable Disease Control↗
PubMed1994

[Educational television].

This author attempted to understand the potential impact of using closed-circuit TV as an educational strategy to meet the learning needs of patients and their families. To do so, she gathered data from two hospitals that offered this avenue for health teaching. Of the 70 patients who participated in the research study, 32 were maternity patients and 38 surgical patients. The data were measured using the MAQSI criteria, which the Ordre des infirmières et infirmiers du Québec uses to measure quality of nursing care. The results revealed that although TV has many practical educational applications, TV in itself did not have a significant impact on learning. The hospital with the most significant learning had integrated closed-circuit TV education into the nursing care plan. The author also found that many factors could influence the impact that educational programming had on patients. Examples include the time selected for viewing or the length of stay in hospital. However, the key to the successful use of TV as an educational tool in the hospital setting seems to lie in the integration of TV learning with other conventional teaching methods.

Humans↗
PubMed1993

Evidence for the presence of five distinct proteolytic components in the pituitary multicatalytic proteinase complex. Properties of two components cleaving bonds on the carboxyl side of branched chain and small neutral amino acids.

Initial studies on the specificity of the multicatalytic proteinase complex (MPC; EC 3.4.99.46) led to the identification of three distinct proteolytic components designated as trypsin-like, chymotrypsin-like, and peptidylglutamyl-peptide hydrolyzing, all sensitive to inactivation by 3,4-dichloroisocoumarin (DCI), a general serine proteinase inhibitor. The three components cleave the peptidyl-arylamide bonds in the model synthetic substrates, Z-(D)-Ala-Leu-Arg-2-naphthylamide, Z-Gly-Gly-Leu-p-nitroanilide, and Z-Leu-Leu-Glu-2-naphthylamide, respectively. We report here evidence for the presence in the MPC of two additional distinct components, neither of them capable of cleaving the three model substrates. One of these components cleaves the Leu-Gly and the Leu-Ala bonds in the substrates Cbz-Gly-Pro-Ala-Leu-Gly-p-aminobenzoate and Cbz-Gly-Pro-Ala-Leu-Ala-p-aminobenzoate, respectively, and is activated by treatment of the MPC with DCI, N-ethylmaleimide, Mg2+, Ca2+, and low concentrations of sodium dodecyl sulfate and fatty acids. This component is apparently identical with the previously identified DCI-resistant component of the MPC that cleaves preferentially bonds on the carboxyl side of branched chain amino acids in natural peptides including neurotensin and proinsulin [Cardozo, C., Vinitsky, A., Hidalgo, M. C., Michaud, C., & Orlowski, M. (1992) Biochemistry 31, 7373-7380]. It is probably also identical with the component proposed to be the main factor responsible for the caseinolytic activity [Pereira, M. E., Nguyen, T., Wagner, B. J., Margolis, J. W., Yu, B., & Wilk, S. (1992a) J. Biol. Chem. 267, 7949-7955]. The designation "branched chain amino acid preferring" (BrAAP) is proposed for this component. The second component cleaves peptide bonds between the small neutral amino acids Ala-Gly and Gly-Gly in the substrates Cbz-Gly-Pro-Ala-Ala-Gly-p-aminobenzoate and Cbz-Gly-Pro-Ala-Gly-Gly-p-aminobenzoate, respectively. This component is sensitive to inactivation by DCI, N-ethylmaleimide, and organic mercurials, but unlike the BrAAP it is significantly activated neither by Mg2+ or Ca2+ nor by fatty acids or sodium dodecyl sulfate. The designation "small neutral amino acid preferring" (SNAAP) is proposed for this component. Both components are sensitive to inhibition by the peptidyl-aldehydes N-acetyl-Leu-Leu-norleucinal (Ac-LLnL-CHO; calpain inhibitor I) and N-acetyl-Leu-Leu-methioninal (Ac-LLM-CHO; calpain inhibitor II) but are resistant to inhibition by Z-LLF-CHO, a potent inhibitor of the chymotrypsin-like activity.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗
PubMed1992

Inhibition of the chymotrypsin-like activity of the pituitary multicatalytic proteinase complex.

The multicatalytic proteinase complex (MPC), also referred to as proteasome, is a large molecular mass intracellular particle (approximately 700 kDa), which exhibits three distinct proteolytic activities designated as chymotrypsin-like, trypsin-like, and peptidylglutamyl-peptide hydrolyzing (PGPH), all sensitive to inhibition by 3,4-dichloroisocoumarin (DCI). The presence of a component resistant to inhibition by DCI with an apparent preference toward bonds on the carboxyl side of branched-chain amino acids has also been recently established. Peptide aldehydes and peptide alpha-keto esters containing a hydrophobic residue in the P1 position have been tested as potential inhibitors of the chymotrypsin-like activity. Three peptide aldehydes (benzyloxycarbonyl)-Leu-Leu-phenylalaninal (Z-LLF-CHO), N-acetyl-Leu-Leu-norleucinal (Ac-LLnL-CHO), and N-acetyl-Leu-Leu-methioninal (Ac-LLM-CHO) were found to be slow-binding reversible inhibitors with Ki values of 0.46, 5.7, and 33 microM, respectively. The simplest kinetic model for inhibition is consistent with a mechanism involving a slow and reversible association of the enzyme with the inhibitor to form a EI complex. The aldehyde inhibitors also inhibited the trypsin-like and PGPH activities of the complex albeit with much higher Ki values than those for chymotrypsin-like activity. Z-LLF-CHO, the most selective of the three aldehydes, did not inhibit the PGPH activity at concentrations of up to 200 microM and inhibited the trypsin-like activity with a Ki approximately 2 orders of magnitude higher than that for the chymotrypsin-like activity. The activity of the DCI-resistant component was not affected by Z-LLF-CHO.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1992

A 3,4-dichloroisocoumarin-resistant component of the multicatalytic proteinase complex.

The multicatalytic proteinase complex (MPC) exhibits three proteolytic activities designated as trypsin-like, chymotrypsin-like, and peptidylglutamyl-peptide hydrolyzing (PGPHA). Evidence based on inhibitor and specificity studies indicates that each of the three activities is associated with a different component of the complex. Inactivation of the three activities by the serine proteinase inhibitor, 3,4-dichloroisocoumarin (DCI), reveals the presence of an additional DCI-resistant component that cleaves natural peptides including neurotensin, dynorphin, angiotensin II, the oxidized B-chain of insulin, and also proinsulin at a rate greater than that of the native uninhibited complex. Examination of the reaction products of neurotensin (NT) and proinsulin degradation showed cleavage of the Ile12-Leu13 bond in NT and cleavage of the Leu44-Ala45 and Val39-Gly40 bonds within the connecting peptide (C-chain) of bovine proinsulin, suggesting preferential cleavage of bonds on the carboxyl side of branched chain amino acids. Although resistant to inhibition by DCI, the component was sensitive to inhibition by the isocoumarin derivatives, 7-amino-4-chloro-3-[3-(isothioureido)propoxy]isocoumarin and 4-chloro-7-guanidino-3-(2-phenylethoxy)isocoumarin. Degradation of NT was activated by leupeptin, chymostatin, and antipain indicating that binding of these aldehyde inhibitors at one site can stimulate proteolytic activity at a different site of the complex. The DCI-resistant component seems to constitute a major component of the complex active in degradation of natural peptides and proteins.

Amino Acid Sequence↗
PubMed1992

[Heart valve surgery and associated diseases in aged subjects].

The object of this study was to assess the additional risk related to associated pathology in patients aged 70 or over undergoing valvular heart surgery. Two hundred and thirty nine patients aged 70 to 87 years (average 74.6 +/- 3.2) underwent this form of surgery between October 1979 and June 1989. Sixty seven had coronary artery disease, 26 had atherosclerotic occlusive peripheral arterial disease, and 149 had one or more extracardiovascular pathology. Two hundred and thirteen patients underwent monovalvular and 26 bivalvular replacement. Coronary bypass was associated in 25 cases. Eighteen patients (7.5%) died in the 30 days following surgery. The perioperative mortality was not significantly greater in patients with extra-cardiac pathology (9.4% vs 4.4%; NS), in patients with coronary artery disease (11.9% vs 5.8%; NS), in patients with respiratory failure and FEV1 < 1 litre (1 death out of 20 cases) or in patients with renal failure and serum creatinine levels > or = 175 mumol/l (20% vs 6.3%, NS). Respiratory failure was the only extra-cardiac variable identified with increased perioperative morbidity. The perioperative mortality of elderly patients with valvular heart disease is greater than that of patients under 70 years of age (6.4% vs 2.1%) in our experience of the last 6 years p < 0.01). Associated arterial and extra-cardiac pathology does not significantly increase the mortality and strict selection of elderly inoperable patients together with improved surgical techniques and postoperative care has considerably reduced perioperative morbidity and mortality in this group of patients.

Aged↗
PubMed1991

Regulation of the peptidylglutamyl-peptide hydrolyzing activity of the pituitary multicatalytic proteinase complex.

The finding that the activity of the multicatalytic proteinase complex (MPC) is greatly activated by low concentrations of sodium dodecyl sulfate (SDS) and fatty acids led to the proposal that the proteolytic activity of the complex is latent and that activation is needed for expression of full activity. Kinetic examination of the nature of the latency with Cbz-Leu-Leu-Glu-2-naphthylamide, a substrate cleaved by the peptidylglutamyl-peptide hydrolyzing activity (PGPH activity) of the complex, showed that plots of velocity versus substrate concentration yield sigmoidal curves, implying the presence of two or more substrate binding sites and the presence of cooperative interactions between the sites. Hill plots of log [v/(Vmax-v)] versus log [S] gave slopes with a Hill coefficient of 2.2-2.4, suggesting that more than two subunits are expressing the PGPH activity. At saturating substrate concentrations, SDS and lauric acid exposed a masked component of PGPH activity that was about equal in magnitude to the overt activity measured in the absence of these detergents, showing that under the latter conditions only about half of the enzyme activity is expressed. Activation by SDS and lauric acid was greater at low than at high substrate concentrations and was associated with a shift of the substrate concentration at half-Vmax (apparent Km) toward lower values. The decrease in the apparent Km in the presence of SDS (but not in the presence of lauric acid) was associated with a decrease in cooperativity. The presence of at least two distinct PGPH activity components with different reactivities was also indicated by the finding of two distinct inactivation rate constants in reactions with 3,4-dichloroisocoumarin, an irreversible inhibitor of the enzyme.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Effects of breakfast-size on short-term memory, concentration, mood and blood glucose.

Effects of breakfast size on blood glucose, mood, short-term memory and concentration were assessed in 319 adolescents (age 13-20 years) in real-life setting. Mean energy increase of 63% over habitual breakfast had no effect on blood glucose or late morning mood. High energy intake from breakfast had a beneficial effect on immediate recall in short-term memory evaluated on the whole sample. However, concentration appeared to be impaired by a high caloric breakfast. There were no differences in the studied parameters according to energy supplement size. The present results are consistent with suggestions that meal size supplement has an effect on cognitive function.

Adolescent↗
PubMed1990

Over-production, purification and properties of the uridine-diphosphate-N-acetylmuramoyl-L-alanyl-D-glutamate: meso-2,6-diaminopimelate ligase from Escherichia coli.

The UDP-N-acetylmuramoyl-L-alanyl-D-glutamate:meso-2,6-diaminopimelate ligase was over-produced and purified from two plasmid-harbouring strains of Escherichia coli. The first strain, E. coli JM83(pHE5), gave a 15-fold over-production relative to parental strain. The enzyme could be partially purified (8.8-fold) by ion-exchange chromatography. With the second strain, E. coli JM83(pMLD25), a very strong over-production was obtained, since the enzyme represented about 20% of the cytoplasmic proteins. Purification yielded 77% protein homogeneity. However, the enzymatic activity, which was very unstable, was lost during the purification procedure. Several properties of the enzyme were studied. The enzyme gave maximal activity around pH 8. The isoelectric point was 5.2. The activity was increased by potassium phosphate. Reverse and exchange reactions could be catalysed. The N-terminal sequence of the protein was determined and correlated with the nucleotide sequence of the murE gene. The actual initiation codon was assigned.

Amino Acid Sequence↗