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Biomedical subjects

J Pous

Publications and source records attributed to J Pous.

At least 19 recordsLinked to original sources
PubMed2002

Crystallization and preliminary X-ray analysis of the DNA decamers d(CCGGATCCGG) and d(CCGGCGCCGG).

The DNA decamers d(CCGGATCCGG) and d(CCGGCGCCGG) have been crystallized for X-ray analysis in order to investigate the effects of changing the two central base pairs of the DNA fragment d(CCGGGACCGG). Previous studies have already demonstrated that the structure of the former DNA fragment contains a DNA Holliday junction. Crystals were obtained at 293 K by the hanging-drop vapour-diffusion technique using the Nucleic Acid Mini Screen. Over a period of two weeks, hexagonal plates appeared. For the DNA fragment d(CCGGATCCGG), the crystals belong to space group P3(1), with unit-cell parameters a = b = 33.54, c = 46.39 A, alpha = beta = 90, gamma = 120 degrees, and diffract to 2.2 A. In the case of the DNA fragment d(CCGGCGCCGG) the crystals belong to the space group C2, with unit-cell parameters a = 65.35, b = 24.07, c = 37.34 A, beta = 109.97 degrees, and diffract to 2.0 A.

Crystallization↗
PubMed2002

Crystallization and preliminary X-ray analysis of the antimalarial and cytotoxic alkaloid cryptolepine complexed with the DNA fragment d(CCTAGG)2.

Crystals of the indoloquinoline alkaloid cryptolepine complexed with the DNA fragment d(CCTAGG)(2) have been grown by the hanging-drop technique at 293 K using ammonium sulfate as the precipitating agent. Over a period of three weeks, yellow tapering bullet-shaped crystals grew to maximum dimensions of 0.2 x 0.1 x 0.1 mm. The crystals belong to space group P6(4), with unit-cell parameters a = b = 29.960, c = 39.64 A, alpha = beta = 90, gamma = 120 degrees, and diffract to 1.4 A.

Alkaloids↗
PubMed2001

The structure of an engineered domain-swapped ribonuclease dimer and its implications for the evolution of proteins toward oligomerization.

BACKGROUND: Domain swapping has been proposed as a mechanism that explains the evolution from monomeric to oligomeric proteins. Bovine and human pancreatic ribonucleases are monomers with no biological properties other than their RNA cleavage ability. In contrast, the closely related bovine seminal ribonuclease is a natural domain-swapped dimer that has special biological properties, such as cytotoxicity to tumour cells. Several recombinant ribonuclease variants are domain-swapped dimers, but a structure of this kind has not yet been reported for the human enzyme. RESULTS: The crystal structure at 2 A resolution of an engineered ribonuclease variant called PM8 reveals a new kind of domain-swapped dimer, based on the change of N-terminal domains between the two subunits. The swapping is fastened at both hinge peptides by the newly introduced Gln101, involved in two intermolecular hydrogen bonds and in a stacking interaction between residues of different chains. Two antiparallel salt bridges and water-mediated hydrogen bonds complete a new interface between subunits, while the hinge loop becomes organized in a 3(10) helix structure. CONCLUSIONS: Proteins capable of domain swapping may quickly evolve toward an oligomeric form. As shown in the present structure, a single residue substitution reinforces the quaternary structure by forming an open interface. An evolutionary advantage derived from the new oligomeric state will fix the mutation and favour others, leading to a more extended complementary dimerization surface, until domain swapping is no longer necessary for dimer formation. The newly engineered swapped dimer reported here follows this hypothetical pathway for the rapid evolution of proteins.

Amino Acid Sequence↗
PubMed2001

Three-dimensional structure of human RNase 1 delta N7 at 1.9 A resolution.

Human pancreatic ribonuclease 1 (RNase 1) is considered to be the human counterpart of bovine pancreatic RNase A. Truncation of seven amino-acid residues from the amino-terminal sequence resulted in RNase 1 Delta N7, which has a reduced ribonucleolytic activity and a lower affinity for the human placental RNase inhibitor (PRI). This RNase 1 variant has been cloned, heterologously overexpressed, purified and crystallized. Its crystal structure has been determined and refined using data to 1.9 A resolution. The molecule displays the alpha + beta folding topology typical of members of the RNase A superfamily. The main distinct features found in RNase 1 Delta N7 are basically located in three loops affecting the fitting of the enzyme to the active site of subtilisin and the shape of the B2 subsite. These changes, taken with the lack of the catalytically active residue Lys7, may explain the reduced affinity of RNase 1 Delta N7 for PRI and the low ribonucleolytic activity of the protein when compared with the native enzyme.

Amino Acid Sequence↗
PubMed2001

[Cost-effectiveness in diagnosis and treatment of carcinomas of unknown primary origin].

The aim was to compare, in terms of cost-effectiveness, two diagnostic strategies for finding out the primary site of tumors revealed by metastasis, adopting the hospital's perspective. The observed strategy reflected the usual practices of doctors at the Regional Cancer Center in Toulouse (France), and was based on a sample of 202 patients of this Center. The standardized strategy, which reflected limited diagnostic investigation, was simulated using the same sample of patients to whom we applied the recommendations of local experts. In the low assumption regarding the effectiveness of the standardized strategy, the observed strategy compared to the standardized one raised the life expectancy from 407 to 418 days at an incremental cost of $US 1,236 per patient (1996 values). In this case, one day of additional life induced a cost of $US 112 per patient. In the high assumption, the incremental effectiveness was null and the incremental cost was $US 1,236 per patient. In conclusion, the effectiveness of the observed strategy as compared to the standardized strategy was highly questionable, given that the patients' quality of life was not taken into account.

Adult↗
PubMed2000

Three-dimensional structure of a human pancreatic ribonuclease variant, a step forward in the design of cytotoxic ribonucleases.

We have determined the crystal structure of a human pancreatic ribonuclease or RNase 1 variant at 1.65 A resolution. Five residues in the N-terminal region were substituted by the corresponding amino acids of the bovine seminal RNase. In addition, a Pro to Ser mutation was present at position 50. The substitution of part of the N terminus has been critical both in improving the expression of this enzyme as a recombinant protein and in achieving its crystallisation. The determination of the crystal structure revealed the characteristic RNase fold including a V-shaped beta-sheet and three alpha-helices. It differs from its bovine RNase orthologue mainly in the loop regions. The active-site cleft shows a similar architecture to that of its bovine counterpart, with the essential residues occupying equivalent positions. In the present structure, however, His119 is displaced as it is in the structure of RNase A at high pH. An interaction model of human ribonuclease with the ribonuclease inhibitor, together with inhibition assays, indicate that, in contrast to RNase A, the modification of the loop beta4beta5 is not enough to avoid inhibition. This study represents the first crystallographic approach to the human enzyme, and should constitute an invaluable tool for the design of ribonuclease variants with acquired cytotoxic properties.

Amino Acid Sequence↗
PubMed2000

Three-dimensional crystal structure of human eosinophil cationic protein (RNase 3) at 1.75 A resolution.

Eosinophil cationic protein (ECP; RNase 3) is a human ribonuclease found only in eosinophil leukocytes that belongs to the RNase A superfamily. This enzyme is bactericidal, helminthotoxic and cytotoxic to mammalian cells and tissues. The protein has been cloned, heterologously overexpressed, purified and crystallized. Its crystal structure has been determined and refined using data up to 1. 75 A resolution. The molecule displays the alpha+beta folding topology typical for members of the ribonuclease A superfamily. The catalytic active site residues are conserved with respect to other ribonucleases of the superfamily but some differences appear at substrate recognition subsites, which may account, in part, for the low catalytic activity. Most strikingly, 19 surface-located arginine residues confer a strong basic character to the protein. The high concentration of positive charges and the particular orientation of the side-chains of these residues may also be related to the low activity of ECP as a ribonuclease and provides an explanation for its unique cytotoxic role through cell membrane disruption.

Amino Acid Sequence↗
PubMed2000

Alzheimer disease: protective factors.

Approximately 6-8% of all persons aged >65 y have Alzheimer disease and the prevalence of the disease is increasing. Any intervention strategy aimed at decreasing risks or delaying the onset of the disease will therefore have a substantial effect on health care costs. Nutrition seems to be one of the factors that may play a protective role in Alzheimer disease. Many studies suggest that oxidative stress and the accumulation of free radicals are involved in the pathophysiology of the disease. Several studies have shown the existence of a correlation between cognitive skills and the serum concentrations of folate, vitamin B-12, vitamin B-6, and, more recently, homocysteine. However, nutritional factors have to be studied not alone but with the other factors related to Alzheimer disease: genetics, estrogen, antiinflammatory drug use, and socioeconomic variables. The objective of this article was to review recent studies in this field.

Aged↗
PubMed1999

Alarm communication network to help carers of the elderly for safety purposes: a survey of a project.

Over years, radical changes in engineering technology have taken place due to greatly improved instrumentation, enhanced computing power, new sensors and upgraded transmission mediums making it possible to achieve in the field what once could only be done on laboratory models. In daily life, the use of an active self-testing instrumentation endowed with a self-diagnostic capability built into the structural fabric of a machine permits us to monitor the initiation of breakdown, corrosion and erosion. This has become particularly important in such means of transportation as planes, boats and automobiles where advanced instrumentation, signal processing and pattern recognition systems operate in fairly conventional structures. By capitalizing on the technological progress in the field of instrumentation and data processing, help can be contemplated for elderly people in nursing homes through detection of abnormal situations. The continued assistance to elderly people is achieved by utilizing a technological system respectful of the elderly's privacy and operating without their active participation.

Activities of Daily Living↗
PubMed1998

Crystallographic analysis reveals the 12-fold symmetry of the bacteriophage phi29 connector particle.

The internal symmetry of the connector or portal particle from the double-stranded DNA bacteriophage phi29 has been examined by X-ray crystallography. This large multimeric structure (420 kDa) is built up by a number of identical subunits of the p10 protein. It connects the head of the virus with the tail and plays a central role in the prohead assembly and DNA packaging. For the first time a bacteriophage connector has been crystallized and X-ray data have been collected up to a resolution of 3.2 A. A self-rotation function has been calculated, unambigously revealing the 12-fold symmetry of the particle and its orientation in the crystal lattice. The orientation has been confirmed by calculating a cross-rotation function using a low resolution model based on electron microscopy reconstructions.

Bacillus Phages↗
PubMed1998

Purification, crystallization and preliminary X-ray diffraction studies of the bacteriophage phi29 connector particle.

The connector or portal particle from double-stranded DNA bacteriophage phi29 has been crystallized. This structure, which connects the head of the virus with the tail and plays a central role in prohead assembly and DNA packaging and translocation, is formed by 12 subunits of the p10 protein and has a molecular weight of 430 kDa. The connector structure was proteolysed with endoproteinase Glu-C from Staphylococcus aureus V8, which removes 13 and 18 amino acids from the amino- and carboxy-terminal regions of the p10 protein, respectively. Two crystal forms were grown from drops containing an alcohol solution and paraffin oil. Crystals of form I are monoclinic, space group C2 with cell dimensions a = 416.86 A, b = 227.62 A, c = 236.68 A and beta = 96.3 degrees and contain four connector particles per asymmetric unit. Crystals of form II are tetragonal, space group P4(2)2(1)2 with cell dimensions a = b = 170.2 A, c = 156.9 A and contain half a particle per asymmetric unit. X-ray diffraction data from both native crystal forms have been collected to 6.0 and 3.2 A respectively, using synchrotron radiation. Crystals of form II are likely to have the same packing arrangement as the two-dimensional crystals analyzed previously by electron microscopy.

Bacillus Phages↗
PubMed1998

Multisensor system and artificial intelligence in housing for the elderly.

To improve the safety of a growing proportion of elderly and disabled people in the developed countries, a multisensor system based on Artificial Intelligence (AI), Advanced Telecommunications (AT) and Information Technology (IT) has been devised and fabricated. Thus, the habits and behaviours of these populations will be recorded without disturbing their daily activities. AI will diagnose any abnormal behavior or change and the system will warn the professionals. Gerontology issues are presented together with the multisensor system, the AI-based learning and diagnosis methodology and the main functionalities.

Activities of Daily Living↗
PubMed1997

[Social situations and health care of immigrant foreign populations in France over the course of the last 5 decades].

The goal of this study is to define possible characteristics in social and medical needs with immigrant foreigners who arrived in France during the last fifty years; and because of the grave situation, it should be necessary to take appropriate and special action. Except identical needs related to similar social and economic situations shared by french and foreign people, the immigration introduces new risk factors: related to ethnologic expression of the illness and cultural breaking, a special assistance is claimed; ethnopsychiatry is one of many possible solutions.

Delivery of Health Care↗
PubMed1997

[Mental and behavior disorders in the aged: attempt at classification and relationship with caregivers' burden].

BACKGROUND: To measure the relation between different disorders of the elderly and the carer's burden. METHOD: A cross-sectional study was carried out by a questionnaire administered to carers of dependent elderly living at home. Mental and behavioral disorders were measured by the Zarit "Memory and behavior problems check list" (MBPC); carer's burden was measured with the Zarit "Burden Inventory" (BI). A principal components analysis was performed to make groups of disorders with the MBPC items and the relation between these groups and the carers' burden was determined by a multiple regression analysis. RESULTS: The analysis was performed with 190 files. Six groups of disorders were individualized: memory and orientation problems, aggressive or dangerous behaviors, regressive behaviors, disruptive behaviors, wandering, mood disturbance and agitation. These 6 factors explain 43.2% of the variance of the carer's burden. Each factor is linked to the BI score and 3 behavioral typologies are specially related to the carers BI: regressive behaviors (R = 0.49), disruptive behaviors (R = 0.51), and mood disturbance with agitation (R = 0.53). CONCLUSION: This study shows that it is possible to differentiate specific behavioral typologies in elderly, which explain a limited part of the carer's burden.

Age Factors↗
PubMed1997

[Predictive factors of institutionalization of dependent elderly persons].

BACKGROUND: This study analyses the factors related to the institutionalization of dependent patients living in the community and receiving informal care from relatives. METHODS: The study is based on a 3-year follow-up of a sample of 205 pairs (carereceiver-caregiver). Eligible care receivers were aged 65 years and over, living at home, and physically or mentally dependent. Caregivers were interviewed at inclusion and three years later in order to know whether the elderly was institutionalized or still living at home. RESULTS: Cox proportional hazards analysis indicated that significant predictors of subsequent institutionalization were intention to institutionalize (p = 0.001), caregiver type (p = 0.015), caregiver's subjective perception of patient behavior problems (p = 0.009), and, at a lesser extent, to live in a urban environment (p = 0.051). The functional status and the carereceiver's age were not predictive of institutionalization. CONCLUSION: This study emphasizes the importance of subjective factors and characteristics of the primary caregiver in predicting institutionalization of elderly dependent persons.

Age Factors↗
PubMed1996

[Measuring the burden for carers of dependent elderly with the Zarit inventory].

The aim of this study was to measure the subjective burden felt by persons who care for dependent elderly people living in their home. A questionnaire was administered to 291 persons. The burden is measured by the Zarit "Burden Inventory" in the French version; it is a 22 question scale exploring the consequences of caring activities in the physical, psychological and social area. The burden score is related to the physical dependency and mostly to the behavioural troubles of the elderly. It is not different according to the carer's family relationship but it is related to his family situation, his self-rated health and the desire to institutionalize the elderly person. This synthetic tool seems to measure the quality of life of carers, but longitudinal studies are necessary to measure its predictive value concerning behaviours in this population.

Activities of Daily Living↗
PubMed1995

Trends in acute myocardial infarction prognosis and treatment in southwestern France between 1985 and 1990 (the MONICA Project-Toulouse).

Since 1984, the Multinational Monitoring of Trends and Determinants in Cardiovascular Disease (MONICA project) has studied progress in acute coronary artery disease (CAD) in defined geographic areas. This study, based in a French MONICA center in Southwestern France, assessed acute myocardial infarction (AMI) frequency, prognosis, and treatment between 1985 and 1990. The age-standardized AMI attack rate showed a slight decrease in men (218.3 of 100,000 in 1985 and 200.1 of 100,000 in 1990, p < 0.05). In men, the AMI age-standardized 28-day case fatality rate decreased from 38% in 1985 to 27% in 1990 (p < 0.001), with a dramatic reduction in the age-standardized in-hospital case fatality rate (21% in 1985 and 11% in 1990, p < 0.001). Furthermore, the in-hospital 28-day case fatality decreased exclusively in male patients with a history of CAD (33% in 1986 and 19% in 1990, p < 0.01). AMI treatment improved between 1986 and 1990 with increased use of antiplatelets (40.7% in 1986, 73.6% in 1989, and 84.8% in 1990, p < 0.001), beta-blockers (29.5% in 1986, 45.7% in 1989, and 57.7% in 1990, p < 0.001), and thrombolytic therapy (23.6% in 1986, 45.3% in 1989, and 39.5% in 1990, p < 0.001). Invasive cardiology technique utilization increased dramatically between 1986 and 1990 with the generalized use of coronary angiography (68.2% in 1986, 89.3% in 1989, and 87.3% in 1990, p < 0.001) and percutaneous transluminal coronary angioplasty (17.7% in 1986, 49.6% in 1989, and 55.3% in 1990, p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗