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Biomedical subjects

C Dumas

Publications and source records attributed to C Dumas.

At least 91 records · Page 5Linked to original sources
PubMed1996

Clinical evaluation of a prototype motion artifact resistant pulse oximeter in the recovery room.

The frequency and nature of spurious pulse oximetry readings were compared using both a conventional pulse oximeter (CPO) and a prototype Masimo signal extraction technology pulse oximeter (Masimo SET). At a university hospital, 50 ASA physical status I-IV adult patients who underwent general or spinal-epidural anesthesia were selected from a group of 250 patients on the basis of high-alarm generation with routine postoperative pulse oximetry. Pulse oximetry data were recorded simultaneously from both devices with a computer. Overall, the CPO alarm frequency (i.e., oxygen saturation < 90%, or complete signal loss) was once every 13 min, and 87% of these alarms were considered false. Alarms were considered false based on reference electrocardiographs (16 patients), arterial blood gases (7 patients), and clinical assessment. The prototype Masimo SET device alarm frequency was once every 30 min, and 59% of these were considered false. During arm motion with 15 patients, the CPO device produced spurious signals on 54 occasions compared with five for the prototype Masimo SET. The incidence of artifactual pulse oximetry events during patient motion appear to be substantially reduced with the prototype Masimo SET device, relative to a CPO device.

Adult↗
PubMed1996

Vigabatrin as initial therapy for infantile spasms: a European retrospective survey. Sabril IS Investigator and Peer Review Groups.

PURPOSE: The efficacy and tolerability of vigabatrin (VGB) as an add-on therapy in the treatment of infantile spasm (IS) prompted physicians to explore its use as the first drug in this seizure type. METHODS: Our retrospective study included 250 infants diagnosed with IS; the data obtained were subjected to peer-group review. Of this infant population, 192 infants were considered to have classic IS and had received VGB as their first treatment for the spasms. There was a slight preponderance of boys (57%) in this population. Mean age of IS onset was 5.8 months; 60% had typical hypsarrhythmia. RESULTS: Initial suppression of spasms was obtained in 68% of infants with a median time to response of 4 days at an average VGB dose of 99 mg/kg/day. The best response was seen in those infants with tuberous sclerosis (96% response) and in those younger than 3 months at onset of spasms (90% response). Of these infants, 43 (22%) of 192 subsequently had other types of seizures, and a recurrence of infantile spasms occurred in 28 (21%) of 131 responders. At the end of this study, 96 of 192 infants who could be evaluated were seizure free with VGB monotherapy. Treatment appeared to be well tolerated, with only 33 (13%) infants with adverse events, of which the most common were somnolence (15 patients) and hyperkinesia (eight patients). In only two cases did adverse events require VGB withdrawal. CONCLUSION: This study supports the opinion that VGB may be considered an initial treatment for IS regardless of cause.

Age of Onset↗
PubMed1996

-Choroidal detachment associated with rhegmatogenous retinal detachment: a risk factor for postoperative PVR?.

PURPOSE: To determine whether preoperative choroidal detachment associated with primary rhegmatogenous retinal detachment is an independent risk factor for postoperative PVR. MATERIAL AND METHODS: One hundred eighty nine primary rhegmatogenous retinal detachments in 187 consecutive patients, initially operated on by the same surgeon, were enrolled in a prospective study. Ten eyes showed preoperative choroidal detachment associated with retinal detachment. Owing to the small number of eyes with preoperative choroidal detachment, we conducted the statistical analysis using the calculation of relative risk. RESULTS: The correlation between preoperative choroidal detachment and preoperative PVR grade C-D was statistically significant (RR: 9.03; confidence interval: 2.91-28). Postoperative PVR occurred, or recurred, in one of the 10 eyes with preoperative choroidal detachment (10%), and 10 of the 179 eyes with no choroidal detachment (5.58%). The difference between the two groups is not statistically significant (RR: 1.79; confidence interval: 0.25-12.64). All eyes which developed postoperative PVR showed one or two recognized independent risk factors for postoperative PVR (preoperative PVR grade C-D and/or retinal tears > or = 90 degrees). CONCLUSION: With the treatment modalities used in the present series (preoperative and postoperative steroids, and vitreoretinal microsurgery) preoperative choroidal detachment associated with primary rhegmatogenous retinal detachment no longer appears to be an independent risk factor for postoperative PVR.

Adult↗
PubMed1996

[Has the incidence of postoperative PVR in rhegmatogenous retinal detachment decreased?].

PURPOSE: To determine whether the incidence of severe postoperative PVR in primary rhegmatogenous retinal detachment has decreased over the last twelve years. MATERIALS AND METHODS: We prospectively evaluated 595 eyes of 554 consecutive patients with primary rhegmatogenous retinal detachment, referred before any failed attempt to reattach the retina, managed by the same surgeon between March 1983 and December 1994. The eyes were divided into two consecutive series: 275 eyes operated on from March 1983 through February 1988 (series no. 1), and 320 eyes operated on from February 1988 through December 1994 (series no. 2). We conducted univariate and multivariate statistical analyses to compare the incidence of postoperative PVR in the two consecutive series. RESULTS: The overall incidence of postoperative PVR was 8.72% (24/275 eyes) in series no. 1, versus 2.81% (9/320 eyes) in series no. 2 (p < 0.01). The incidence of postoperative PVR in retinal detachments due to atrophic holes in lattice degeneration, oral dialyses, and macular holes in myopic eyes, was nil in both series. The incidence of postoperative PVR in retinal detachments due to horseshoe tears with mobile posterior edges was 1.16% (1/86 eyes) in series no. 1, and 0% (0/109 eyes) in series no. 2. The incidence of postoperative PVR in retinal detachments associated with horseshoe tears with curled posterior edges was 21.15% (11/52 eyes) in series no. 1 versus 3.2% (3/93 eyes) in series no. 2 (p < 0.001). The incidence of postoperative PVR in giant tears was 35.5% (11/31 eyes) in series no. 1. and 14.7% (5/34 eyes) in series no. 2 (chi square = 3.77; at the limit of significance). The incidence of postoperative PVR in retinal detachments du to paravascular tears of the post-equatorial region in myopic eyes was 25% (1/4 eyes) in series no. 1, and 14% (1/7 eyes) in series no. 2. CONCLUSION: In our own experience, the incidence of postoperative PVR in primary rhegmatogenous retinal detachment has decreased at a statistically significant level since 1988. We believe that the decreased incidence of postoperative PVR in our most recent series is mainly related to the use of laser photocoagulation retinopexy rather than cryopexy in the management of high risk eyes (retinal detachments associated with horseshoe tears with curled posterior edges, and giant tears).

Adolescent↗
PubMed1995

Phasing with mercury at 1 A wavelength.

Synchrotron sources provide a continuously tunable X-ray beam which makes it possible to optimize the anomalous contribution to phase determination using heavy-atom replacement. This method was used to solve two protein structures, those of Dictyostelium discoideum nucleoside diphosphate kinase and of lobster enolase. The first had 17 kDa of protein in the asymmetric unit, the second, 47 kDa. In both cases, a single mercury derivative yielded single isomorphous replacement with anomalous-scattering phases from which an interpretable electron-density map was derived by solvent flattening. The efficient solution of the X-ray structure was largely due to the large anomalous scattering of mercury at a wavelength shorter than the L(III) absorption edge.

Journal Article↗
PubMed1995

SLR3: a modified receptor kinase gene that has been adapted to encode a putative secreted glycoprotein similar to the S locus glycoprotein.

A new member of the S gene family, SLR3 (S-Locus Related 3), was identified in Brassica oleracea. This gene had a novel pattern of expression compared with previously described members of the family, being expressed in petals, sepals and vegetative apices, in addition to stigmas and anthers. Moreover, use of SLR3-derived probes in RNA blot and RACE-PCR (rapid amplification of cDNA ends-polymerase chain reaction) experiments has identified transcripts of genes closely related to SLR3 in leaves, cotyledons and, at high levels in developing anthers. SLR3 is not linked to the S locus but is linked to two or three closely related genes. Sequence analysis of the SLR3 gene indicates that it is derived from an ancestral receptor kinase gene that has been modified by a series of deletion events. As a result of these modifications, SLR3 is predicted to encode a secreted glycoprotein lacking both transmembrane and kinase domains. The putative SLR3 protein differs from the products of most other S gene family members in that several of the highly conserved cysteines have been lost. Within the S gene family, modification of receptor kinase genes by deletion may represent a general mechanism for the generation of genes encoding secreted glycoproteins.

Amino Acid Sequence↗
PubMed1995

PCR-generated cDNA library of transition-stage maize embryos: cloning and expression of calmodulin genes during early embryogenesis.

One hundred maize zygotic embryos microdissected at the transition stage were used to construct a cDNA library after non-selective PCR (NS-PCR) amplification of whole cDNA populations. The library contains 2.3 x 10(5) recombinants and two different calmodulin cDNAs were cloned using a heterologous probe from petunia. Calmodulin expression was confirmed throughout maize embryogenesis at the mRNA, amplified cDNA and protein levels. Sequence analysis suggests a maize origin for both clones and negligible nucleotide changes linked to PCR. This library is the first described for early plant embryos and represents a breakthrough to isolate genes involved in embryo differentiation.

Amino Acid Sequence↗
PubMed1995

Expression level of the SLG gene is not correlated with the self-incompatibility phenotype in the class II S haplotypes of Brassica oleracea.

In Brassica, the S-locus glycoprotein (SLG) gene has been strongly implicated in the self-incompatibility reaction. Several alleles of this locus have been sequenced, and accordingly grouped as class I (corresponding to dominant S-alleles) and class II (recessive). We recently showed that a self-compatible (Sc) line of Brassica oleracea expressed a class II-like SLG (SLG-Sc) gene. Here, we report that the SLG-Sc glycoprotein is electrophoretically and immunochemically very similar to the recessive SLG-S15 glycoprotein, and is similarly expressed in stigmatic papillae. Moreover, by seed yield analysis, we observed that both alleles are associated with a self-compatibility response, in contrast with the other known recessive S haplotypes (S2 and S5). By genomic DNA blot analysis, we show the existence of molecular homologies between the Sc and S15 haplotypes, but demonstrate that they are not identical. On the other hand, we also report that the S2 haplotype expresses very low amounts of SLG glycoproteins, although it exhibits a self-incompatible phenotype. These results strongly question the precise role of the SLG gene in the molecular mechanisms that control the self-incompatibility reaction of Brassica.

Alleles↗
PubMed1995

Expression of heat shock factor and heat shock protein 70 genes during maize pollen development.

We have analysed the expression of heat shock protein 70 (HSP70) and heat shock factor (HSF) gene during maize pollen development, HSFs being the transcriptional activators of hsp genes. In order to eliminate the sporophytic tissues of anthers, we have isolated homogeneous cell populations corresponding to five stages of maize pollen development from microspores to mature pollen. We show that in the absence of heat stress, hsp70 genes are highly expressed late-bicellular pollen as compared to other stages. HSP70 transcripts are significantly accumulated in response to a heat shock at the late microspore stage but to a much lower extent than in vegetative tissues. The latest stages of pollen development, i.e. mid-tricellular and mature pollen, do not exhibit heat-induced accumulation of HSP70 transcripts. Therefore, we analysed the expression of hsf genes throughout pollen development. We demonstrate that at least three hsf genes are expressed in maize and that transcripts corresponding to one hsf gene, whose expression is independent of temperature in somatic as well as in microgametophytic tissues, are present at similar levels throughout pollen development. In addition, we show that the expression of the two other hsf genes is heat-inducible in maize vegetative tissues and is not significantly increased after heat shock at any stage of pollen development. These results indicate that the loss of hsp gene expression at late stages of pollen development is not due to a modification of hsf gene expression at the mRNA level and that hsf gene expression is differentially regulated in vegetative and microgametophytic tissues.

Amino Acid Sequence↗
PubMed1995

Pharmacokinetic, metabolic, and antidiarrheal properties of (D and L) heptapeptides of sorbin in rodent.

The C-terminal heptapeptide-amide (C7-sorbin) is the minimal biologically active fragment of sorbin inducing an increase in intestinal hydroelectrolytic absorption. An analogue (D7-sorbin), characterized by the replacement of the ultimate C-terminal amino acid L-alanine-amide by D-alanine-amide, was synthetized. For pharmacokinetic studies, D7-sorbin and C7-sorbin were tritium labeled. After IV injection, clearances were 10.6 and 30.2 ml-1 for D7-sorbin and C7-sorbin, respectively, and MRT were 34 and 18 min. After SC administration, Cmax attained 0.41% and 0.12% of the dose/ml, respectively. The IP route showed a 45-min delay before Cmax and a 100% bioavailability for both peptides. D7-sorbin was principally excreted in urine, as shown by balance study, and in part in intact form, as controlled by mass spectrometry. D7-sorbin induced a significant decrease of the VIP-induced ileal secretion, previously observed with C7-sorbin. The change of L-Ala to D-Ala increased the stability of the synthetic C-terminal peptide of sorbin whereas its biological activity, bioavailability, and route of elimination were unchanged.

Animals↗
PubMed1995

Characterization of the S locus genes, SLG and SRK, of the Brassica S3 haplotype: identification of a membrane-localized protein encoded by the S locus receptor kinase gene.

The S locus, which controls the self-incompatibility response in Brassica, has been shown to contain at least two genes. SLG encodes a secreted S locus glycoprotein whilst SRK encodes a putative S locus receptor kinase. SRK has been shown potentially to encode a functional kinase and genetic evidence indicates that this gene is essential for the self-incompatibility response. Here the characterization of the SRK and SLG genes of a Brassica line homozygous for the S3 haplotype is described. A 120 kDa glycoprotein was identified in stigmas and several lines of evidence indicated that this protein is encoded by the SRK3 gene. First, the 120 kDa glycoprotein was recognized by antibodies raised against peptides based on the SRK3 gene sequence. Secondly, this protein is polymorphic and, in an F2 population segregating for the S3 haplotype, was expressed only in plants possessing the S3 haplotype. Thirdly, the 120 kDa protein was expressed specifically in stigmas. Finally, the 120 kDa protein was only extracted from stigmas in the presence of detergent indicating that it is anchored in the membrane. SRK has been predicted to encode a transmembrane glycoprotein based on the deduced amino acid sequence. Located on the membrane, SRK is in a position to interface between an extracellular recognition event between pollen and pistil and an intracellular signal transduction pathway which initiates the self-incompatibility response.

Amino Acid Sequence↗
PubMed1995

The S locus receptor kinase gene encodes a soluble glycoprotein corresponding to the SKR extracellular domain in Brassica oleracea.

Self-incompatibility in Brassica is controlled by the S locus which contains at least two genes. SLG encodes a secreted S locus glycoprotein whilst SRK encodes a putative S locus receptor kinase which consists of three domains: an extracellular domain sharing extensive sequence identity with SLG, transmembrane region, and a cytoplasmic domain exhibiting a serine/threonine protein kinase activity. Here, the existence of truncated forms of the SRK protein corresponding to the extracellular domain of the putative receptor is reported. These proteins were detected by an antibody which recognizes the N-terminus of SRK3 and, in an F2 progeny segregating for the S3 haplotype, were only expressed in plants possessing the S3 haplotype. The truncated SRK proteins were expressed specifically in stigmas but, unlike the membrane-spanning SRK3 protein, were soluble and occurred as four different glycoforms sharing the same amino acid backbone as shown by deglycosylation experiments. Several SRK3 transcripts that may code for these truncated SRK3 proteins have been identified by RACE PCR, stigma cDNA library screening and RNA blot analysis. These transcripts are apparently generated by a combination of alternative splicing and the use of alternative polyadenylation signals. The existence of truncated forms of the S locus receptor kinase highlights some similarities between plant and animal receptor kinases. In animals, soluble extracellular domains of receptors have been described and, in some cases, have been shown to play a role in the modulation of signal transduction. By analogy, the soluble, truncated SRK proteins may play a similar role in the self-incompatibility response.

Amino Acid Sequence↗
PubMed1994

Characterization of canine pancreas kallikrein cDNA.

Using a combination of primer extension and RT-PCR, the cDNA encoding a canine tissue kallikrein expressed in the pancreas was cloned and sequenced. The cloned 0.85 kbp cDNA contained a complete open reading frame encoding a polypeptide of 261 amino acids. The calculated molecular mass of the processed, unglycosylated, 237 amino acid protein was 26,428 Da. Its mRNA was expressed at high levels in the pancreas, kidney and submaxillary gland. The sequence of the encoded protein was highly homologous with canine prostatic arginine esterase (66%) and human renal/pancreatic kallikrein (74%). Therefore, the cloned cDNA encoded a previously uncharacterized canine kallikrein enzyme which was named dog renal/pancreatic kallikrein or dK2 according to the new nomenclature for kallikrein gene family members. Because of its specific pattern of tissue expression and the presence of all the amino acid residues necessary for kininogenase activity, we suggest that dK2 is the canine true tissue kallikrein.

Amino Acid Sequence↗
PubMed1994

Adenosine 5'-diphosphate binding and the active site of nucleoside diphosphate kinase.

The X-ray structure of nucleoside diphosphate kinase (NDP kinase) from the slime mold Dictyostelium discoideum has been determined to 2.2-A resolution and refined to an R-factor of 0.19 with and without bound ADP-Mg2+. The nucleotide binds near His 122, a residue which becomes phosphorylated during the catalytic cycle. The mode of binding is different from that observed in other phosphokinases, and it involves no glycine-rich sequence. The adenine base makes only nonpolar contacts with the protein. It points outside, explaining the lack of specificity of NDP kinase toward the base. The ribose 2'- and 3'-hydroxyls and the pyrophosphate moiety are H-bonded to polar side chains. A Mg2+ ion bridges the alpha- to the beta-phosphate which approaches the imidazole group of His 122 from the N delta side. The geometry at the active site in the ADP-Mg2+ complex suggests a mechanism for catalysis whereby the gamma-phosphate of a nucleoside triphosphate can be transferred onto His 122 with a minimum of atomic motion.

Adenosine Diphosphate↗
PubMed1994

Analysis of the cytosolic hsp70 gene family in Zea mays.

In this study we have analysed the multigene family coding for the cytoplasmic heat shock 70 kDa proteins (hsp70) in Zea mays. Fully degenerate primers were used in a polymerase chain reaction (PCR) to amplify selected regions of the hsp70 genes. Sequence and Southern blot analysis reveals that at least three highly conserved genes exist in maize. In addition, amplification reveals the presence of a conserved intron in all genes examined. Expression analysis shows that the hsp70 genes studied represent members of the inducible and constitutive families. The results obtained may indicate that there are subfamilies of cytoplasmic hsp70 genes expressed in higher plants.

Amino Acid Sequence↗
PubMed1994

Pharmacokinetics and organ distribution of the sorbin C-terminal peptides.

Sorbin is a 153 amino acid peptide isolated from porcine small intestine. The heptapeptide-amide is the minimal active site of the natural molecule. A comparison of the distribution of C-7 and C-20 sorbin, which have been shown to share the activity of sorbin in increasing intestinal absorption of electrolytes, was undertaken by radioimmunoassay, after perfusion of 200 micrograms/kg/h. A longer half-life in plasma was observed for C-20 sorbin than for C-7 sorbin, with a clearance rate of 18 +/- 4 ml/min/kg vs. 40.6 +/- 13.5 ml/min/kg and a distribution volume of 192 +/- 35 ml/kg vs. 286 +/- 123 ml/kg. The accumulation of tritiated C-7 sorbin was observed in enterocytes, serosal acini of the salivary glands, and fundus chief cells. The recovery of intact peptide in the intestine was 0.06% per gram of tissue. Eighteen percent of the peptide was detected in urine.

Amino Acid Sequence↗
PubMed1994

Insecticidal and cytotoxic effects of natural and hemisynthetic destruxins.

The insecticidal and cytotoxic effects of 13 natural and hemisynthetic destruxins have been studied. DE shows insecticidal effects similar to those of DA, while DE and DA are more active than all the other natural compounds and analogues tested. Brominated destruxin is a relatively active analogue displaying particular modalities of cytotoxic effects which reflect a certain originality of its mode of action. The linear molecule resulting from the opening of the DA cycle is not toxic. The most hydrophilic destruxins showing e.g. charged radicals (COO-) appear the least toxic probably because they do not penetrate easily the cellular membranes.

Administration, Oral↗