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Biomedical subjects

C Richaud

Publications and source records attributed to C Richaud.

At least 37 records · Page 2Linked to original sources
PubMed1990

[Long-term evaluation of the treatment results of male urethral stenosis].

287 urethral strictures were treated between 1974 and 1984. Two-stage urethroplasty provided 47.6% of good results at 5 years, although there was a possibility of very delayed recurrences. Endoscopic urethrotomy only gave 26% of good results at 5 years, while 30% of good results were obtained after dilatation with Olbert's sound. Endourethral techniques do not compete with two-stage urethroplasty, provided they are performed repeatedly.

Catheterization↗
PubMed1989

Expression of recombinant diaminopimelate epimerase in Escherichia coli. Isolation and inhibition with an irreversible inhibitor.

Recombinant diaminopimelate epimerase is overproduced to give 1% of soluble protein when grown under the appropriate conditions in Escherichia coli. This compares with 0.02% of the constitutive level of wild-type enzyme. A new purification procedure now yields milligram quantities of homogeneous enzyme of high specific activity (192 U/mg). This has enabled sufficient amounts of enzyme both to compare with wild-type enzyme and to enable active site modification studies to be performed. Incubation of the enzyme with 2-(4-amino-4-carboxybutyl)-2-aziridine-carboxylic acid (AZIDAP), results in time-dependent irreversible inhibition. Tryptic digestion of the inactivated enzyme and peptide-mapping show that AZIDAP is specifically and covalently bound to the enzyme at a unique peptide. Determination of the amino acid sequence of this peptide and comparison with the sequence deduced from the DNA sequence of the dapF gene shows that Cys73 is labelled. Finally based on limited sequence similarities around this cysteine and active-site cysteines of proline racemase and 1-hydroxyproline 2-epimerase, together with mechanistic considerations, we propose that all three non-pyridoxal-phosphate-containing racemases/epimerases derive from a common evolutionary origin.

Amino Acid Isomerases↗
PubMed1989

Effect of CO2 and O2 on development and fructification of wheat in closed systems.

The cultivation of wheat (Triticum aestivum L.) was performed in controlled environment chambers with the continuous monitoring of photosynthesis, dark respiration, transpiration and main nutrient uptakes. A protocol in twin chambers was developed to compare the specific effects of low O2 and high CO2. Each parameter is able to influence photosynthesis but different effects are obtained In the development, fructification and seed production, because of the different effects of each parameter on the ratio of reductive to oxidative cycle of carbon. The first main conclusion is that low level of O2, at the same rate of biomass production, strongly acts on the rate of ear appearance and on seed production. Ear appearance was delayed and seed production reduced with a low O2 treatment (approximately 4%). The O2 effect was not mainly due to the repression of the oxidative cycle. The high CO2 treatment (700 to 900 microl l-1) delayed ear appearance by 4 days but did not reduce seed production. High CO2 treatment also reduced transpiration by 20%. Two hypothesis were proposed to explain the similarities and the difference in the O2 and CO2 effects on the growth of wheat.

Biomass↗
PubMed1989

Linear chromosome of Borrelia burgdorferi.

The DNA organization of several European and American isolates of Borrelia burgdorferi, the aetiological agent of Lyme disease, was analysed in pulse-field agarose gel electrophoresis. The results of in situ cell lysis in agarose plugs demonstrated a unique arrangement for the DNA of this spirochete. The chromosome of Borrelia behaved as a eukaryotic linear chromosome with a size of around 1,000 kb. The genome also comprised several circular and linear plasmids which varied in size from 15 to 60 kb.

Borrelia burgdorferi Group↗
PubMed1989

Does medical treatment of lymphedema act by increasing lymph flow?

The lymphatic origin of chronic edema of the lower limbs was identified by lymphoscintigraphic exploration. Patients underwent therapy involving 8 days of manual lymph drainage combined with elevation of the limbs during rest periods and double compression bandaging. Manual drainage increased lymph flow in 16 limbs, implying that the edema resulted from a functional lymphatic anomaly. In contrast, manual drainage did not increase lymph flow in 9 limbs, suggesting a structural anomaly of the lymphatics. Hence, the same clinical picture corresponded to two different lymphatic anomalies, distinguished by lymphoscintigraphy. However, the therapeutic results were independent of the lymphoscintigraphic results. Increased lymph flow is therefore not the only explanation for the decrease in edema during therapy.

Adolescent↗
PubMed1988

Incorporation of LL-diaminopimelic acid into peptidoglycan of Escherichia coli mutants lacking diaminopimelate epimerase encoded by dapF.

Recently a dapF mutant of Escherichia coli lacking the diaminopimelate epimerase was found to have an unusual large LL-diaminopimelic acid (LL-DAP) pool as compared with that of meso-DAP (C. Richaud, W. Higgins, D. Mengin-Lecreulx, and P. Stragier, J. Bacteriol. 169:1454-1459, 1987). In this report, the consequences of high cellular LL-DAP/meso-DAP ratios on the structure and metabolism of peptidoglycan were investigated. For this purpose new efficient high-pressure liquid chromatography techniques for the separation of the DAP isomers were developed. Sacculi from dapF mutants contained a high proportion of LL-DAP that varied greatly with growth conditions. The same was observed with the two DAP-containing precursors, UDP-N-acetylmuramyl-tripeptide and UDP-N-acetylmuramyl-pentapeptide. The limiting steps for the incorporation of LL-DAP into peptidoglycan were found to be its addition to UDP-N-acetylmuramyl-L-alanyl-D-glutamate and the formation of the D-alanyl-DAP cross-bridges. The Km value of the DAP-adding enzyme for LL-DAP was 3.6 x 10(-2) M as compared with 1.1 x 10(-5) M for meso-DAP. When isolated sacculi were treated with Chalaropsis N-acetylmuramidase and the resulting soluble products were analyzed by high-pressure liquid chromatography, the proportion of the main peptidoglycan dimer was lower in the dapF mutant than in the parental strain. Moreover, the proportion of LL-DAP was higher in the main monomer than in the main dimer, where it was almost exclusively located in the donor unit. There are thus very few D-alanyl-LL-DAP cross-bridges, if any. We also observed that large amounts of LL-DAP and N-succinyl-LL-DAP were excreted in the growth medium by the dapF mutant.

Amino Acid Isomerases↗
PubMed1988

[Diagnostic and therapeutic problems posed by renal or para-renal masses of cystic appearances].

The authors report some forty cases of renal masses, cystic in appearance and having raised a certain number of diagnostic or therapeutic problems. These masses included 7 cystic carcinomas, 3 benign tumors of cystic appearance and 28 cysts including 2 infected and 2 hydatid cysts. No paraclinical investigation is infallible in confirming the nature of the mass in doubtful cases, and pre-operative diagnosis is more easily obtained by investigation including the majority of standard imaging methods often completed by puncture. Amongst clinical factors which raise doubts as to the benign nature of the cystic mass seen, hematuria remains the most important, other symptoms and signs being of little significance. With regard to imaging, septate calcified masses with echoes within them, with a thick wall or high CT scan density are theoretically suspect. The same applies to masses having rapidly increased at two successive investigations or where puncture fluid is bloody. In all cases if proof of the benign nature cannot be obtained, surgical exploration would appear to be required.

Calcinosis↗
PubMed1987

Purification and characterization of RNA polymerase from the cyanobacterium Anabaena 7120.

A procedure for the purification of RNA polymerase from vegetative cells of the filamentous cyanobacterium Anabaena 7120 is described. Polyethyleneimine precipitation followed by gel filtration and affinity chromatography steps results in greater than 99% purification with 46% yield. The enzyme has a novel core component of Mr = 66,000, designated gamma, in addition to the typical prokaryotic beta'beta alpha 2 core enzyme. The sigma subunit has been identified by reconstitution of specific transcriptional activity from core enzyme and gel-purified sigma. In transcription assays, this RNA polymerase initiates at a number of Anabaena vegetative cell promoters, as well as from a bacteriophage T4 early promoter, but does not initiate at nitrogen fixation (nif) promoters used in heterocysts. The promoter specificity of Anabaena RNA polymerase is compared with that of Escherichia coli RNA polymerase.

Base Sequence↗
PubMed1987

Molecular cloning, characterization, and chromosomal localization of dapF, the Escherichia coli gene for diaminopimelate epimerase.

The Escherichia coli dapF gene was isolated from a cosmid library as a result of screening for clones overproducing diaminopimelate epimerase. Insertional mutagenesis was performed on the cloned dapF gene with a mini-Mu transposon, leading to chloramphenicol resistance. One of these insertions was transferred onto the chromosome by a double-recombination event, allowing us to obtain a dapF mutant. This mutant accumulated large amounts of LL-diaminopimelate, confirming the blockage in the step catalyzed by the dapF product, but did not require meso-diaminopimelate for growth. The dapF gene was localized in the 85-min region of the E. coli chromosome between cya and uvrD.

Amino Acid Isomerases↗
PubMed1987

[Study and treatment of erection disorders. Value of intracavernous injections].

A multidisciplinary study of 57 patients with erection disorders included in addition to standard examinations: clinical, hormonal, vascular using Doppler and nervous with determination of latency time of bulbocavernous reflex, evaluation of effects of intracavernous papaverine injections completed by a manometric study of cavernous body filing by perfusion. A clear positive result of the papaverine test is considered to reflect integrity of vascularization of corpus cavernosum structure, and renders value less the continuation of vascular investigations. The appearance of an almost normal but delayed erection requiring high-dose papaverine administration is interpreted as being due to insufficiency of arterial origin without anomaly of venous return. The absence of erection after papaverine injection, whether in the presence or absence of an increase in penis volume, results from excessive venous return, insufficient arterial supply or both. Absence of erection despite a cavernous perfusion of more than 70 ml/min is due to excessive venous return that requires localization by cavernography. The onset of erection during cavernous body filling eliminates excessive venous return and results from arterial insufficiency that necessitates pelvic arteriography. A therapeutic attitude of logical consequence is proposed.

Clinical Trials as Topic↗
PubMed1987

[Vascular anomalies of the kidney. Apropos of 3 cases].

Two cases of rare vascular lesions of kidney are reported: a patient with a renal angioma and one with an aneurysm acquired after an oster type endocarditis. Both lesions were detected after severe hemorrhage and nephrectomy was performed in each case. Exact diagnosis was dependent on histopathologic findings. The relevant literature is reviewed.

Adult↗
PubMed1986

Chromosomal location and nucleotide sequence of the Escherichia coli dapA gene.

In Escherichia coli, the first enzyme of the diaminopimelate and lysine pathway is dihydrodipicolinate synthetase, which is feedback-inhibited by lysine and encoded by the dapA gene. The location of the dapA gene on the bacterial chromosome has been determined accurately with respect to the neighboring purC and dapE genes. The complete nucleotide sequence and the transcriptional start of the dapA gene were determined. The results show that dapA consists of a single cistron encoding a 292-amino acid polypeptide of 31,372 daltons.

Base Sequence↗
PubMed1986

[Acute epididymitis].

A series of 86 cases of acute epididymitis observed over a period of 3 years is analyzed and findings reported. Testicular lesions were frequent and 35% of these cases involved a purulent testicular pocket. The epididymal lesion was usually of a total nature (77% of cases), only the tail of the epididymis being involved in 17%. Sterile urine was a frequent finding (50% of cases). Chlamydiae were rarely identified, but administration of medication ineffective against chlamydiae was effective in most cases, suggesting that these organisms are a rare cause of acute epididymitis. Iatrogenic epididymitis was a frequent diagnosis when compared with epididymitis due to cases of known cervico-urethral obstruction. Catheterization, endoscopic resection of prostate, transvesical prostatic adenomectomy were the main cause in the absence of ligature of deferens, the latter being considered as a certain preventive procedure. The affection is possible in children or adolescents (3 cases between 10 and 16 years) with an acute hydrocele as the presenting sign. Tuberculosis is still a possible cause (5 cases) with Koch's bacillus present in the urine in 4 of these patients. In the majority of cases, however, the etiology was unknown (62 of 86 patients = 72%). Treatment can be by a cycline as sole therapy, anti-inflammatory steroid or non-steroid agents also being effective. Medical treatment was rapidly and totally effective in 56 of the 86 patients, but residual foci were noted in 19 of 86 cases. Epididymectomy may be necessary for painful lesions or recurrence of epididymitis, while castration may be indicated (6 cases) for fistula formation, purulent pockets of testis, or ischemic necrosis of testis.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗