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Biomedical subjects

L Richard

Publications and source records attributed to L Richard.

At least 55 records · Page 3Linked to original sources
PubMed1996

Identification by STS PCR screening of a microdeletion in Xp21.3-22.1 associated with non-specific mental retardation.

X-linked non-specific mental retardation (MRX) is a heterogeneous condition in which mental retardation (MR) appears to be the only consistent manifestation. The genetic and phenotypic heterogeneity exclude any possibility of pooling families and, therefore, of fine-mapping the related disease genes. In order to identify genomic critical regions involved in the MRX condition assigned to Xp21.3-22.1 region, we have implemented the PCR screening of non fragile X MR patients for the presence of deletions in this region. The amplification by PCR of 12 markers located between POLA and DXS704 using genomic DNA from 192 MR males led to the identification, in a 9 year old mentally retarded boy, of a microdeletion which extends from DXS1202 to DXS1065. None of the known genes, POLA, MAGE genes cluster, DAX1, GK and DMD, that map in the Xp21.3-22.1 region is affected by this deletion. This approach, which could easily be applied to several other MRX loci, allowed not only a confirmation of the presence of a potential locus in Xp21.3-22.1 involved in non-specific mental retardation, but also a better definition of the genomic critical region corresponding to this locus.

Child↗
PubMed1996

Biological effects of electric and magnetic fields on productivity of dairy cows.

Sixteen multiparous Holstein cows (weighing 600 +/- 50 kg, in 184.8 +/- 52 d of lactation, and at 101.9 +/- 43 d of gestation) were confined to wooden metabolic cages and exposed to a vertical electric field of 10 kV/ m and to a uniform horizontal magnetic field of 30 microT (microtesla). The trial was conducted as a switch-back statistical design. Cows were divided into two replicates of 8 cows each. One replicate was exposed for three periods of 28 d each. During the first period, the electric and magnetic fields were off; during the second period, they were on; and, during the final period, they were off. The second replicate was exposed for three periods also, but the activity of the fields was reversed (first period, on; second period, off; and third period, on). Blood samples were obtained twice weekly for the determination of cortisol and progesterone and once weekly for the determination of pH and blood gases. Milk samples were collected once weekly to determine milk components (fat, protein, SNF, and SCC). Milk yield and feed consumption were measured daily. Most of the variables studied (bicarbonate, pH, O2 and CO2 partial pressures, cortisol concentration in blood, uncorrected milk yield, and milk components other than milk fat) showed no variation that could be attributed to exposure to electric and magnetic fields. Associations were found between the electric and magnetic fields and increased DMI, 4% FCM yield, milk fat content, and plasma progesterone.

Animals↗
PubMed1996

Apoptosis and vascular wall remodeling in hypertension.

Vascular structure plays a key role in the pathogenesis of hypertension. Because it is less readily reversible than protein accumulation, DNA accumulation in the arterial wall may be considered as a record of past episodes of vascular growth, contributing to the persistence of the vascular disease. Apoptosis, a ubiquitous and highly regulated form of programmed cell death that is involved in tissue morphogenesis and homeostasis as the essential counterpart of cell replication, is potentially involved in the regulation of vascular structure, via the deletion of cells in the vessel wall. We discuss how the current knowledge on apoptosis may provide insights into the pathogenesis of vascular wall remodeling, with an emphasis on the biology of vascular smooth muscle cells. Evidence suggests that heightened cell replication rates are often associated with increased apoptosis, as for smooth muscle cells in genetic hypertension or in arterial repair after injury. However, apoptotic cell death may also be regulated independently of cell growth. The triggering of apoptosis depends on a balance of environmental cues that are not specific to apoptosis. However, there is a common set of key biochemical events mediating apoptosis (i.e., committing the cell to die), thus providing a basis for the design of novel pharmacological strategies specifically targeting apoptotic cell death. The identification of biochemical markers of apoptosis and other methodological advances will ultimately help in understanding the role of apoptotic cell death in vascular remodeling and hypertensive end-organ damage.

Animals↗
PubMed1996

[Uretero-acetabular fistula: report of a case].

We present a case report of uretero-acetabular fistula in a female complicating orthopaedic surgery of congenital coxal difformity. An ileal pedicle graft was used to replace the terminal ureter. The difficulty of such complication is to choose the best the rapeutic strategy between surgical and non surgical techniques. We review here the various urological armamentarium to affront such a rare and multifactorial complication.

Acetabulum↗
PubMed1995

Characterization of three members of the ACC synthase gene family in Solanum tuberosum L.

Two genomic clones corresponding to three members of the 1-aminocyclopropane-1-carboxylic acid (ACC) synthase gene family in potato (Solanum tuberosum L.) have been isolated and sequenced. Two highly homologous genes, ST-ACS1A and ST-ACS1B, transcribed in opposite directions were found in an 8.9 kb region. Their coding sequences are interrupted by two introns at identical positions. Their closest relative in tomato is the LE-ACS3 gene. The third gene in potato, ST-ACS2, was found in a 4 kb region and shows a gene structure similar to that of the tomato LE-ACS4 gene and to the mung bean VR-ACS4 and VR-ACS5 genes. Based on its lack of significant homology to the tomato gene family and its closeness to the VR-ACS4 and VR-ACS5 genes, we propose that LE-ACS7 represents an additional isoform in the tomato genome. Moreover, in a phylogenetic comparison of known ACC synthases, the ST-ACS2 isoform was grouped in a separate lineage together with the mung bean VR-ACS4 and VR-ACS5, and the moth orchid DS-ACS1A and DS-ACS1B gene products. Expression of the three potato genes was studied by reverse transcription-polymerase chain reaction on total RNA. The twin genes are positively regulated by indole-3-acetic acid in hypocotyls and expression is modulated by wounding in the leaves. The third gene is responsive to ethylene and wounding mainly in tubers. The roles of these three genes and of other members of the ACC synthase gene family in vegetative processes of potato such as tuberization, dormancy, and sprouting have yet to be determined.

Amino Acid Sequence↗
PubMed1995

Apoptosis in target organs of hypertension.

Apoptosis or programmed cell death frequently parallels abnormalities in cell proliferation and differentiation. As hypertrophy/hyperplasia or remodeling occurs in organs affected by hypertension, we evaluated the degree of apoptosis in the heart, kidney, and brain in situ in genetically hypertensive mice and rats as well as in cultured vascular smooth muscle cells. Apoptosis was characterized by morphological features, DNA fragmentation, and laddering as well as by terminal deoxynucleotidyl transferase labeling of the 3' OH ends of both extracted DNA and tissue sections. The present report provides the first evidence of increased apoptosis in whole organs of genetically hypertensive rat and mouse strains: in the heart of spontaneously hypertensive rats (SHR) and in the heart (ventricular cardiomyocytes), kidney (inner cortex and medulla), and brain (cortex, striatum, hippocampus, and thalamus) of spontaneously hypertensive mice, with a higher effect of apoptotic inducers in cultured aortic smooth muscle cells derived from SHR. Both types of known apoptotic processes, oligonucleosomal cleavage and large DNA fragmentation, were observed in vascular smooth muscle cells, but only the former appeared to be increased in SHR. This study underlines the importance of cell death dysregulation in hypertension, reveals a new route for investigation of the pathogenesis of hypertension, and suggests novel targets of therapeutic intervention.

Animals↗
PubMed1994

Molecular cloning and characterisation of a putative pectin methylesterase cDNA in Arabidopsis thaliana (L.).

Pectin methylesterase (PME) is a cell wall enzyme that catalyses the de-esterification of pectins leading to fundamental changes which confer new properties to the micro-environment of each cell. In order to elucidate the meaning of PME-mediated changes of pectin in the time course of cell differentiation, we attempted to study the regulation of PME genes in Arabidopsis thaliana. In this report, the first full cDNA sequence showing sequence similarities with other PME genes characterised so far in other plant species has been isolated from an Arabidopsis shoot cDNA library. This ATPMEl cDNA is 1,970 bp long and contains an open reading frame encoding a protein of 64.1 kDa and a basic pI of 8.7 as predicted from the nucleotide sequence. Northern blot analyses denoted changes in the expression level of the ATPMEl mRNA according to plant organs. High mRNA levels were found in young developing organs such as cauline leaves while they were significantly lower in rosette leaves, stems and inflorescences, and almost undetectable in roots. Beside this molecular approach, isoelectrofocusing analyses revealed the occurrence of three PME isoforms in Arabidopsis. Two PME isoforms with pI values of 4.9 and 9.1 were found throughout the plant, but at a higher level in the root, while an other PME isoform with a pI of 5.7 was essentially detected in the inflorescence. The relationship between our observations and the data reported for other plant species is discussed.

Amino Acid Sequence↗
PubMed1994

Genes of stress in experimental hypertension.

1. A significant portion of blood pressure variance is modified by the environment. 2. The present report summarizes evidence that: (i) the environmental response is genetically determined; (ii) various stressors can evoke a differential response in hypertensive animals and constitute its intermediate phenotypes; (iii) the response to heat stress can be assigned to a single 'thermosensitivity' locus; (iv) candidate genes of susceptibility to environmental stresses are member(s) of the heat stress gene (HSP) gene families; (v) a restriction fragment length polymorphism of hsp70 and a single base mutation in the 3'-untranslated region of hsp27 are associated with hypertension in recombinant inbred strains. 3. In conclusion, HSP gene variants may be causative in susceptibility to hypertension.

Animals↗
PubMed1994

[Darier-Ferrand dermatofibrosarcoma. Apropos of a case with frontal involvement].

One case of dermato-fibro-sarcoma protuberans is reported on a 36 years old man. It was an extensive forehead tumor which needed a radically surgical treatment. These excision called a reconstruction with cutaneous graft and scalp flaps. Three years after treatment, there was no evidence of recurrence or lymphadenopathy. The aesthetic results is good. The authors recalled with this observation the important points of this disease particularly characterized by slow invasive growth and local recurrence.

Adult↗
PubMed1994

[Lesions of the renal pedicle in blunt abdominal trauma in children. 7 cases].

The frequency of urinary tract trauma in children is difficult to estimate. Renal pedicle lesions are estimated to represent 10% of all forms of urinary tract trauma. These lesions are difficult to diagnose and may be completely missed. Over a 12 year period, we have treated 7 children with a renal pedicle injury. Haematuria was immediate in 3 cases, delayed in 2 cases and absent in 2 cases. The diagnosis is based on intravenous urography or postcontrast computed tomography. Treatment consisted of disobstruction with intimal suture with a good result, but impaired renal function, an upper pole nephrectomy, functional aorto-renal bypass graft but with altered renal function, total nephrectomy and 3 cases of surveillance with one non-functioning kidney. None of these children are hypertensive. The authors discuss the diagnostic approach, the contribution of imaging and the therapeutic options and results.

Abdominal Injuries↗
PubMed1993

HIV-1 and HCV co-infected patients: detection of active viral expression using a nested polymerase chain reaction.

The aim of the present study was to determine, in a population of 70 HIV-1 infected patients with antibodies to HCV, the percentages of individuals with an active replication of HIV-1, HCV or both. During a one year follow-up of these patients at different stages of disease, blood samples were regularly collected for determination of transaminase, beta 2 microglobulin and CD4+ lymphocytes. Total RNAs were extracted from the sera, retrotranscribed with MoMuLV reverse transcriptase and nested PCR assays were carried out separately with sets of primers homologous to the 5' non-translated region of HCV and in HIV-1 gag. The amplified products were subjected to electrophoresis and observed under u.v. illumination after staining with ethidium bromide. For some samples, the identity of the amplified products was confirmed by Southern blotting by hybridization with enzyme-labelled probes. A total of 57% of the patients were found to produce HIV-1 RNA and 62% HCV RNA, while 34% produced both. HIV-1 RNA production was correlated with beta 2 microglobulin and CD4+ levels; active replication of HCV was correlated with hepatitis but not with CD4+ levels nor with HIV-1 RNA synthesis.

Base Sequence↗
PubMed1993

Detection of HCV-RNA in saliva of patients with chronic hepatitis C.

Previous studies have provided conflicting results on the presence of hepatitis C virus-RNA in saliva. In this study, 23 (62%) of 37 patients tested positive for hepatitis C virus-RNA in saliva, using polymerase chain reaction analysis. A slightly greater proportion had a sporadic rather than a parenteral origin of chronic hepatitis C. These results provide a biological basis for saliva as a possible source of hepatitis C virus (HCV) infection, but do not necessarily imply transmission by this route.

Adult↗
PubMed1993

[Periosteal or juxtacortical chondroma of the mandibular condyle].

One case of juxtacortical chondroma is reported, and the authors review the clinical, radiological, pathological and therapeutic data concerning this tumour which was first individualised by Lichtenstein and Hall in 1952 but never described in this location. Conservative surgery with complete excision of the chondroma usually results in permanent cure.

Adult↗
PubMed1992

Picosecond phase grating spectroscopy of hemoglobin and myoglobin: energetics and dynamics of global protein motion.

Phase grating spectroscopy has been used to follow the optically triggered tertiary structural changes of carboxymyoglobin (MbCO) and carboxyhemoglobin (HbCO). Probe wavelength and temperature dependencies have shown that the grating signal arises from nonthermal density changes induced by the protein structural changes. The material displaced through the protein structural changes leads to the excitation of coherent acoustic modes of the surrounding water. The coupling of the structural changes to the fluid hydrodynamics demonstrates that a global change in the protein structure is occurring in less than 30 ps. The global relaxation is on the same time scale as the local changes in structure in the vicinity of the heme pocket. The observed dynamics for global relaxation and correspondence between the local and global structural changes provides evidence for the involvement of collective modes in the propagation of the initial tertiary conformational changes. The energetics can also be derived from the acoustic signal. For MbCO, the photodissociation process is endothermic by 21 +/- 2 kcal/mol, which corresponds closely to the expected Fe-CO bond enthalpy. In contrast, HbCO dissipates approximately 10 kcal/mol more energy relative to myoglobin during its initial tertiary structural relaxation. The difference in energetics indicates that significantly more energy is stored in the hemoglobin structure and is believed to be related to the quaternary structure of hemoglobin not present in the monomeric form of myoglobin. These findings provide new insight into the biomechanics of conformational changes in proteins and lend support to theoretical models invoking stored strain energy as the driving force for large amplitude correlated motions.

Carboxyhemoglobin↗