Biomedical subjects

C Denis

Publications and source records attributed to C Denis.

At least 37 records · Page 2Linked to original sources

PubMed2001

High level of alpha2-adrenoceptor in rat foetal liver and placenta is due to alpha2B-subtype expression in haematopoietic cells of the erythrocyte lineage.

1. Rat foetal liver contains large amounts of alpha2-adrenoceptors. The present work aimed to identify the receptor subtype and the cell type accounting for high expression and to clarify the mechanisms responsible for the sharp decrease in hepatic receptivity occurring during the late stage of foetal development. 2. Binding experiments indicated that the density of alpha2-adrenoceptors in the foetal liver (embryonic day 18; 615+/-155 fmol mg(-1) of protein) is 18 fold higher than in newborn or adult (35.2+/-4.3 fmol mg(-1)). A high amount of receptor is also found in the placenta (443+/-53 fmol mg(-1)). In both tissues, the rank order of antagonists to inhibit radioligand binding matched the pharmacological profile of the alpha2B-adrenoceptor and exclusively RNG transcripts were detected by RNase protection assays. 3. Isolation of cell fractions from foetal liver showed that alpha2B-adrenoceptor is primarily expressed by haematopoietic cells. Consistent with this view, the receptor is found to be abundant in foetal blood, carried by reticulocytes. The expression in blood gradually declines to zero at 3 weeks of age and it is not recovered following induction of reticulocytosis in adults. 4. In foetal reticulocytes, a low proportion of the receptor population is coupled to G-protein. The alpha2-agonist UK14304 has a marginal effect on cyclic AMP level but significantly increases arachidonic acid release. The function of the receptor remains to be elucidated. However, together with observations on alpha2B-knockout mice, the current finding strongly suggests a role for alpha2B-adrenoceptor during foetal haematopoiesis in rodents.

Adrenergic alpha-Agonists↗

PubMed2001

Leg power and hopping stiffness: relationship with sprint running performance.

PURPOSE: Although sprint performance undoubtedly involves muscle power, the stiffness of the leg also determines sprint performance while running at maximal velocity. Results that include both of these characteristics have not been directly obtained in previous studies on human runners. We have therefore studied the link between leg power, leg stiffness, and sprint performance. METHODS: The acceleration and maximal running velocity developed by 11 subjects (age 16 +/- 1) during a 40-m sprint were measured by radar. Their leg muscle volumes were estimated anthropometrically. Leg power was measured by an ergometric treadmill test and by a hopping test. Each subject executed a maximal sprint acceleration on the treadmill equipped with force and speed transducers, from which forward power was calculated. A hopping jump test was executed at 2 Hz on a force platform. Leg stiffness was calculated using the flight and contact times of the hopping test. RESULTS: The treadmill forward leg power was correlated with both the initial acceleration (r = 0.80, P < 0.01) and the maximal running velocity (r = 0.73, P < 0.05) during track sprinting. The leg stiffness calculated from hopping was significantly correlated with the maximal velocity but not with acceleration. CONCLUSION: Although muscle power is needed for acceleration and maintaining a maximal velocity in sprint performance, high leg stiffness may be needed for high running speed. The ability to produce a stiff rebound during the maximal running velocity could be explored by measuring the stiffness of a rebound during a vertical jump.

Adolescent↗

PubMed2001

Influence of training on NIRS muscle oxygen saturation during submaximal exercise.

PURPOSE: Endurance training improves the oxygen delivery and muscle metabolism. Muscle oxygen saturation measured by near infrared spectroscopy (IR-SO(2)), which is primarily influenced by the local delivery/demand balance, should thus be modified by training. We examined this effect by determining the influence of change in blood lactate and muscle capillary density with training on IR-SO(2) in seven healthy young subjects. METHODS: Two submaximal exercise tests at 50% (Ex1) and 80% pretraining VO(2max) (Ex2) were performed before and after a 4-wk endurance-training program. RESULTS: VO(2max) increased only slightly (+8%, NS) with training but the training effect was confirmed by the increased capillary density (+31%, P < 0.01) and citrate synthase activity (50%, P < 0.01), determined from muscle biopsy samples. Before training, blood lactate increased during the first 5 min of Ex1 and then remained constant (3.8 +/- 0.5 mmol x L(-1), P < 0.01), whereas it increased continuously during Ex2 (8.9 +/- 1.8 mmol x L(-1), P < 0.001). After training, lactate decreased significantly and remained constant during the two bouts of exercise (2.0 +/- 0.4 and 3.7 +/- 1.2 at the end of Ex1 and Ex2, respectively, both P < 0.001). During Ex1, IR-SO(2) dropped initially at the onset of exercise and recovered progressively without reaching the resting level. Training did not change this pattern of IR-SO(2). During Ex2, IR-SO(2) decreased progressively during the 15 min of exercise (P < 0.05); IR-SO2 kept constant after the initial drop after training. We found a significant relationship (r = 0.42, P = 0.03) between blood lactate and IR-SO(2) at the end of both bouts of exercise; this relationship was closer before training. By contrast, IR-SO(2) or IR-BV was not related to the capillary density. CONCLUSION: The training-induced adaptation in blood lactate influences IR-SO(2) during mild- to hard-intensity exercise. Thus, NIRS could be used as a noninvasive monitoring of training-induced adaptations.

Adult↗

PubMed2001

Modulation of alpha-ENaC and alpha1-Na+-K+-ATPase by cAMP and dexamethasone in alveolar epithelial cells.

cAMP and dexamethasone are known to modulate Na+ transport in epithelial cells. We investigated whether dibutyryl cAMP (DBcAMP) and dexamethasone modulate the mRNA expression of two key elements of the Na+ transport system in isolated rat alveolar epithelial cells: alpha-, beta-, and gamma-subunits of the epithelial Na+ channel (ENaC) and the alpha1- and beta1-subunits of Na+-K+-ATPase. The cells were treated for up to 48 h with DBcAMP or dexamethasone to assess their long-term impact on the steady-state level of ENaC and Na+-K+-ATPase mRNA. DBcAMP induced a twofold transient increase of alpha-ENaC and alpha1-Na+-K+-ATPase mRNA that peaked after 8 h of treatment. It also upregulated beta- and gamma-ENaC mRNA but not beta1-Na+-K+-ATPase mRNA. Dexamethasone augmented alpha-ENaC mRNA expression 4.4-fold in cells treated for 24 h and also upregulated beta- and gamma-ENaC mRNA. There was a 1.6-fold increase at 8 h of beta1-Na+-K+-ATPase mRNA but no significant modulation of alpha1-Na+-K+-ATPase mRNA expression. Because DBcAMP and dexamethasone did not increase the stability of alpha-ENaC mRNA, we cloned 3.2 kb of the 5' sequences flanking the mouse alpha-ENaC gene to study the impact of DBcAMP and dexamethasone on alpha-ENaC promoter activity. The promoter was able to drive basal expression of the chloramphenicol acetyltransferase (CAT) reporter gene in A549 cells. Dexamethasone increased the activity of the promoter by a factor of 5.9. To complete the study, the physiological effects of DBcAMP and dexamethasone were investigated by measuring transepithelial current in treated and control cells. DBcAMP and dexamethasone modulated transepithelial current with a time course reminiscent of the profile observed for alpha-ENaC mRNA expression. DBcAMP had a greater impact on transepithelial current (2.5-fold increase at 8 h) than dexamethasone (1.8-fold increase at 24 h). These results suggest that modulation of alpha-ENaC and Na+-K+-ATPase gene expression is one of the mechanisms that regulates Na+ transport in alveolar epithelial cells.

Animals↗

PubMed2000

High incidence of biallelic point mutations in the Runt domain of the AML1/PEBP2 alpha B gene in Mo acute myeloid leukemia and in myeloid malignancies with acquired trisomy 21.

The AML1 gene, situated in 21q22, is often rearranged in acute leukemias through t(8;21) translocation, t(12;21) translocation, or less often t(3;21) translocation. Recently, point mutations in the Runt domain of the AML1 gene have also been reported in leukemia patients. Observations for mutations of the Runt domain of the AML1 gene in bone marrow cells were made in 300 patients, including 131 with acute myeloid leukemia (AML), 94 with myelodysplastic syndrome (MDS), 28 with blast crisis chronic myeloid leukemia (CML), 3 with atypical CML, 41 with acute lymphoblastic leukemia (ALL), and 3 with essential thrombocythemia (ET). Forty-one of the patients had chromosome 21 abnormalities, including t(8;21) in 6 of the patients with AML, t(12;21) in 8 patients with ALL, acquired trisomy 21 in 17 patients, tetrasomy 21 in 7 patients, and constitutional trisomy 21 (Down syndrome) in 3 patients. A point mutation was found in 14 cases (4.7%), including 9 (22%) of the 41 patients with AML of the Mo type (MoAML) (none of them had detectable chromosome 21 rearrangement) and 5 (38%) of the 13 myeloid malignancies with acquired trisomy 21 (1 M1AML, 2 M2AML, 1 ET, and 1 atypical CML). In at least 8 of 9 mutated cases of MoAML, both AML alleles were mutated: 3 patients had different stop codon mutations of the 2 AML1 alleles, and 5 patients had the same missense or stop codon mutation in both AML1 alleles, which resulted in at least 3 of the patients having duplication of the mutated allele and deletion of the normal residual allele, as shown by FISH analysis and by comparing microsatellite analyses of several chromosome 21 markers on diagnosis and remission samples. In the remaining mutated cases, with acquired trisomy 21, a missense mutation of AML1, which involved 2 of the 3 copies of the AML1 gene, was found. Four of the 7 mutated cases could be reanalyzed in complete remission, and no AML1 mutation was found, showing that mutations were acquired in the leukemic clone. In conclusion, these findings confirm the possibility of mutations of the Runt domain of the AML1 gene in leukemias, mainly in MoAML and in myeloid malignancies with acquired trisomy 21. AML1 mutations, in MoAML, involved both alleles and probably lead to nonfunctional AML1 protein. As AML1 protein regulates the expression of the myeloperoxidase gene, the relationship between AML1 mutations and Mo phenotype in AML will have to be further explored. (Blood. 2000;96:2862-2869)

Acute Disease↗

PubMed2000

Odds and Trends: Recent Developments in the Chemistry of Odorants Note on trademarks: Words which we know or have reason to believe constitute registered trademarks (R) are designated as such. However, neither the presence nor absence of such designation should be regarded as affecting the legal status of any trademark. Note on perfume analysis: The quoted percentages of perfume raw materials in market products are rounded figures. They are often derived from area percentages from the GC (FID) analysis, and are thus subject to analytical error.

Fragrance chemistry is, together with the closely related area of flavor chemistry, one of the few domains, if not the only one, in which chemists can immediately experience structure-activity relationships. This review presents structure-odor correlations and olfactophore models for the main odor notes of perfumery: "fruity", "marine", "green", "floral", "spicy", "woody", "amber", and "musky". New trendsetters and so-called captive odorants of these notes are introduced, and recent activities and highlights in fragrance chemistry are summarized. The design of odorants, their chemical synthesis, and their use in modern perfumery is discussed. Our selection is guided and illustrated by creative fragrances, and features new odorants which encompassed current trends in perfumery. New odorants for grapefruit and blackcurrant, for galbanum, and leafy top notes are presented. Compounds with fashionable marine, ozonic, and aquatic facets are treated, as well as new odorants for classical lily-of-the-valley, rose, and jasmine accords. Compounds with sweet and spicy tonalities are also discussed, as are the most recent developments for woody notes such as sandalwood and vetiver. We conclude with musky and ambery odorants possessing uncommon or unusual structural features. Some odor trends and effects are illustrated by microencapsulated fragrance samples, and areas where there is need for the development of new synthetic materials and methodologies are pointed out. Thus, chemists are invited to explore fragrance chemistry and participate in the design and synthesis of new odorants. This review gives the latest state of the art of the subject.

Journal Article↗

PubMed2000

Involvement of low-density lipoprotein receptor-related protein (LRP) in the clearance of factor VIII in von Willebrand factor-deficient mice.

Factor VIII is tightly noncovalently linked to von Willebrand factor (vWF) in plasma with a stoichiometry of 1:50, and vWF deficiency results in secondary factor VIII deficiency, with accelerated clearance of factor VIII from the circulation. We used a murine model of severe von Willebrand disease (vWF knockout mice) to study the effect of a recombinant vWF/pro-vWF preparation (rpvWF) on factor VIII survival and to investigate whether low-density lipoprotein receptor-related protein (LRP) might be involved in the in vivo clearance of factor VIII in the absence of vWF. vWF-deficient mice received 70 U/kg rpvWF in the first series of experiments, and in a second series, 80 mg/kg receptor-associated protein (RAP) as a recombinant fusion protein to block the action of LRP. Factor VIII levels were measured at time 0, or 1 or 3 hours after administration of rpvWF or RAP. RAP induced a sustained rise in factor VIII levels comparable to that induced by rpvWF. In a third series, the preadministration of RAP resulted in a slower disappearance of factor VIII antigen (measured by an enzyme-linked immunosorbent assay specific for human factor VIII) after infusion of recombinant factor VIII. These findings suggest that the accelerated clearance of factor VIII seen in the absence of vWF may be a result of the involvement of LRP in factor VIII metabolism. (Blood. 2000;95:1703-1708)

Animals↗

PubMed2000

FISH analysis with a YAC probe improves detection of LAZ3/BCL6 rearrangement in non-Hodgkin's lymphoma.

INTRODUCTION: Chromosomal translocations involving the chromosome 3q27 region are common in B-cell non-Hodgkin's lymphoma (NHL), mainly diffuse large cell lymphoma (DLCL) and less often in follicular lymphoma. Most of these rearrangements involve the same major translocation cluster (MTC) on the 3q27 region, disrupting the LAZ3/BCL6 gene. Some of those translocations are difficult to detect by cytogenetic analysis and/or Southern-blot analysis. In the present report we used a FISH assay to improve the detection of LAZ3/BCL6 rearrangements. METHODS: We isolated a YAC clone (803g3), containing the BCL6 gene, in order to analyze by FISH 19 cases of B-cell non-Hodgkin's lymphoma with cytogenetically detectable 3q27 rearrangement, including reciprocal translocation in 11 cases, deletion in two cases, and addition of undefined chromosomal material on 3q27 in six cases. RESULTS: In the 11 cases with reciprocal translocation, FISH results confirmed cytogenetic data and showed disruption of the LAZ3 region: four t(3;4)(q27;p13), two t(3;11)(q27;q23.1), four t(3;14)(q27;q32) and one t(2;3)(p12;q27). In two of the cases, reciprocal t(3;14) was associated with other cytogenetically detectable abnormalities of 3q27, but FISH showed that they did not affect the LAZ3 gene region. FISH demonstrated a reciprocal translocation with LAZ3 gene rearrangement in two of the six patients with add 3q27: one t(3;11) and one t(3;14). In the two patients with del(3q27), one had two 3q27 FISH signals and one had only one 3q27 FISH signal, but no LAZ3 gene rearrangement was observed. CONCLUSION: We have identified a YAC containing the LAZ3/BCL6 gene. This YAC probe could be useful in clinical practice to demonstrate LAZ3 rearrangements by FISH analysis on tumor samples in NHL.

Blotting, Southern↗

PubMed2000

Effect of hyperoxia on aerobic and anaerobic performances and muscle metabolism during maximal cycling exercise.

The hyperoxia-improved tolerance to maximal aerobic performance was studied in relation to exercising muscle metabolic state. Five students were submitted to four different tests on a cycle ergometer, each being conducted under normoxia and hyperoxia (60% FiO2) on separate days: Test 1, a progressive exercise until exhaustion to determine the maximal work load (Wmax) which was unchanged by hyperoxia; Test 2, an exercise at Wmax (287 +/- 12 W) until exhaustion to determine the performance time (texh) which was elevated by 38% under hyperoxia but exhaustion occurred at the same arterial proton and lactate concentrations; Test 3 (S-Exercise test) consisted of cycling at Wmax for 90% normoxic-texh (4.8 +/- 0.5 min under both O2 conditions) then followed by a 10-s sprint bout during which the total work output (Wtot) was determined; Wtot was elevated by 15% when exercising under hyperoxia; Test 4 (M-Exercise test) consisted also of cycling at Wmax for 4.8 +/- 0.5 min with blood and muscle samples taken at rest and at the end of the exercise to compare the level of different metabolites. During hyperoxic M-Exercise test, glycogen was twice more depleted whereas glucose-6-phosphate and lactate were less accumulated when compared with normoxia. No significant differences were observed for pyruvate, phosphocreatine and muscle/blood lactate ratio between the two conditions. Conversely to normoxia, levels of ATP, ADP and total NADH were maintained at their resting level under 60% FiO2. These data lead us to suppose a higher oxidation rate for pyruvate and NADH in mitochondria, thereby lowering the metabolic acidosis and allowing a better functioning of the glycolytic and contractile processes to delay the time to exhaustion.

Adult↗

PubMed2000

Transcriptional down-regulation of the human alpha2C-adrenergic receptor by cAMP.

The heterologous regulation of the alpha2C-adrenergic receptor (alpha2C-AR) was investigated in the HepG2 cell line. Binding of [(3)H]MK912 (alpha2-antagonist) to membranes from cells submitted to various treatments showed that exposure to insulin, phorbol 12-myristate 13-acetate, or dexamethasone did not affect receptor density. On the other hand, treatment with forskolin resulted in a large reduction of alpha2C-AR number. The effect of forskolin was mimicked by 8-br-cAMP and was abolished by the protein kinase A inhibitor, H89. The action of cAMP was slow (t(1/2) = 23 h), dose-dependent, and additive to the receptor down-regulation elicited by the alpha2-agonist, UK14304. Furthermore, the diminution of receptor was not caused by an increased rate of its degradation but resulted from a decrease in the steady state amounts of alpha2C4-mRNA. As assessed by experiments in the presence of actinomycin D, the stability of alpha2C4-mRNA was not affected by 8-br-cAMP or forskolin. By contrast, the activity of a luciferase construct containing the entire promoter region of the alpha2C4 gene (1.9 kilobase pairs) was inhibited, indicating that the primary mechanism of action of the two compounds is at the transcriptional level. Deletions in the 5'-end of this construct showed that the elements responsible for cAMP responsiveness lie within a 242-base-pair fragment of the gene promoter (nucleotides -236/+6 relative to transcription start). Band-shift experiments indicated that nuclear factors bind to this region in a cAMP-dependent manner. The determination of the actual cis- and trans-acting elements involved will be the object of future investigation, but the present study provides evidence for transcriptional regulation of human alpha2C-AR by cAMP.

8-Bromo Cyclic Adenosine Monophosphate↗

PubMed2000

Alpha(2) adrenoceptors regulate proliferation of human intestinal epithelial cells.

BACKGROUND AND AIMS: Previous studies on rodents have suggested that catecholamines stimulate proliferation of the intestinal epithelium through activation of alpha(2) adrenoceptors located on crypt cells. The occurrence of this effect awaits demonstration in humans and the molecular mechanisms involved have not yet been elucidated. Here, we examined the effect of alpha(2) agonists on a clone of Caco2 cells expressing the human alpha(2A) adrenoceptor. METHODS: Cells were transfected with a bicistronic plasmid containing the alpha2C10 and neomycin phosphotransferase genes. G418 resistant clones were assayed for receptor expression using radioligand binding. Receptor functionality was assessed by testing its ability to couple Gi proteins and to inhibit cAMP production. Mitogen activated protein kinase (MAPK) phosphorylation was followed by western blot, and cell proliferation was estimated by measuring protein and DNA content. RESULTS: Permanent transfection of Caco2 cells allowed us to obtain a clone (Caco2-3B) expressing alpha(2A) adrenoceptors at a density similar to that found in normal human intestinal epithelium. Caco2-3B retained morphological features and brush border enzyme expression characteristic of enterocytic differentiation. The receptor was coupled to Gi2/Gi3 proteins and its stimulation caused marked diminution of forskolin induced cAMP production. Treatment of Caco2-3B with UK14304 (alpha(2) agonist) induced a rapid increase in the phosphorylation state of MAPK, extracellular regulated protein kinase 1 (Erk1), and 2 (Erk2). This event was totally abolished in pertussis toxin treated cells and in the presence of kinase inhibitors (genistein or PD98059). It was unaffected by protein kinase C downregulation but correlated with a transient increase in Shc tyrosine phosphorylation. Finally, sustained exposure of Caco2-3B to UK14304 resulted in modest but significant acceleration of cell proliferation. None of these effects was observed in the parental cell line Caco2. CONCLUSION: The results obtained in the present study support a regulatory role for alpha(2) adrenoceptors in intestinal cell proliferation.

Adrenergic alpha-2 Receptor Agonists↗

PubMed1999

Detection of BCR-ABL transcripts in chronic myeloid leukemia (CML) using an in situ RT-PCR assay.

Methods of minimal residual disease (MRD) detection in chronic myelogenous leukemia (CML) include chromosome analysis, reverse transcriptase polymerase chain reaction (RT-PCR) and fluorescence in situ hybridization (FISH) techniques. We report a novel method to detect intracellular BCR-ABL messenger on single cells using in situ RT-PCR, which can be performed on blood and marrow slides, without extraction of the nucleic acid. After cellular permeabilization and fixation, the mRNA BCR-ABL was reverse transcribed and amplified by PCR using digoxigenin-labelled dUTP. The reaction was revealed with the anti-digoxigenin FITC antibody. On the fluorescent microscope, a strong positive green fluorescence signal was observed in 98-99% cells in Ph1-positive cell lines. A faint signal was detected in 1.5% and 2% of negative cell lines. Likewise, a faint signal was found in 1.6-2.8% of the cells in five normal controls (mean 2.2 +/- 1.1%). The positive threshold for in situ RT-PCR was therefore determined as mean + 2 s.d. = 4.4% cells. We used in situ RT-PCR by comparison to cytogenetics (at least 30 mitoses examined), and two-step RT-PCR (10(-6) sensitivity in our hands) in bone marrow samples from 13 CML patients: two patients at diagnosis and 11 patients in hematological remission after alpha interferon (three patients), hydroxyurea (one patient) autologous bone marrow transplantation (BMT) (one patient) and allogeneic BMT (six patients). In the two diagnostic patients, 90 and 95% cells were respectively strongly positive by in situ RT-PCR. In the six patients treated by allogeneic BMT, the median percentage of positive cells was 2.4% (range 1.8-3.2). All six patients had normal karyotype and negative two-step RT-PCR results. In the five other patients, two were treated by hydroxyurea alone or autologous BMT, and 11 and 13% of the cells were strongly positive; three were treated with interferon and 14-62% of the cells were positive, generally weakly. All five patients had persistence of Ph1 (in 9-56% mitoses), and positive RT-PCR results after one round. In conclusion, in situ RT-PCR can specifically identify cells with BCR-ABL transcript and its results are concordant with those of karyotype and RT-PCR. Because of its limited sensitivity and specificity, however, it appears to have limited value in the analysis of MRD. On the other hand, it can evaluate the presence and intensity of BCR-ABL fusion transcript at the single cell level, and this could be useful in treatment monitoring.

Bone Marrow Transplantation↗

PubMed1999

Age-associated alteration of muscle oxygenation measured by near infrared spectroscopy during exercise.

The influence of ageing on the capacity to increase muscle oxygen delivery during exercise is unclear. This was investigated by comparing the evolution of Near InfraRed Spectroscopy (NIRS) in 10 old (67 +/- 5 years, Old group) and 13 young subjects (27 +/- 4 years, Young group), during a progressive maximal exercise. The NIRS probe was placed on the vastus lateralis; muscle oxygen saturation - IR-SmO(2) - values were expressed on a scale using an arterial occlusion as the lower reference point and the subsequent reactive hyperaemia as the upper reference point. Resting IR-SmO( 2) was found to be significantly lower in the Old as co mpared to the Young group. During exercise, VO(2) increased similarly as a function of the workload whereas IR-SmO(2) decreased faster in old subjects than in young ones. Conversely, when expressed at the same percentage of VO( 2max), IR-SmO(2) followed a similar evolution in both groups from rest to maximal exercise (27.3 +/- 16.7 vs 24.3 +/- 12.9% decrease, in Old and Young group, respectively, NS). Thus, the initial difference remained constant between the two groups. During recovery, the time to recover the signal variation was not different between the two groups. We concluded that Old subjects demonstrate a systematic lower muscle oxygen saturation than Young ones. This difference could be explained by an age related decrease in muscle blood flow limiting O(2) supply.

Adult↗

PubMed1999

Nonrandom fusion of L-plastin(LCP1) and LAZ3(BCL6) genes by t(3;13)(q27;q14) chromosome translocation in two cases of B-cell non-Hodgkin lymphoma.

The LAZ3(BCL6) gene on chromosome band 3q27 is nonrandomly disrupted in B-cell non-Hodgkin lymphoma (B-NHL) by chromosomal translocations clustered within a 3.3-kb MTC (major translocation cluster) located between the two first noncoding exons. These translocations generally result in the expression of a chimeric mRNA transcript between the LAZ3 gene and sequences derived from the partner chromosome. Using RACE RT-PCR, we previously demonstrated fusion of LAZ3 with the RhoH/TTF gene, a hemopoietic cell-specific small GTPase involved in cytoskeleton organization, and with the BOB1/OBF1 gene, a B-cell-specific coactivator of octamer-binding transcription factors, following translocations t(3;4)(q27;p13) and t(3;11)(q27;q23), respectively. Here we report the identification of the L-Plastin(LCP1) gene as a novel LAZ3 partner in chimeric transcripts resulting from a t(3;13)(q27;q14) translocation, in two cases of B-cell lymphoma. As a consequence of the translocation, the 5' regulatory region of each gene was exchanged, creating both LCP1-LAZ3 and reciprocal LAZ3-LCP1 fusion transcripts in one case, and only a LCP1-LAZ3 fusion transcript in the other. The 13q14 chromosome region is frequently disrupted in various proliferative disorders, and the LCP1 gene defines a new breakpoint site in this region. This gene encodes an actin-binding protein and is the second LAZ3 partner gene, with the RhoH/TTF gene, involved in actin cytoskeleton organization. Genes Chromosomes Cancer 26:97-105, 1999.

Base Sequence↗

PubMed1998

A mouse model of severe von Willebrand disease: defects in hemostasis and thrombosis.

von Willebrand factor (vWf) deficiency causes severe von Willebrand disease in humans. We generated a mouse model for this disease by using gene targeting. vWf-deficient mice appeared normal at birth; they were viable and fertile. Neither vWf nor vWf propolypeptide (von Willebrand antigen II) were detectable in plasma, platelets, or endothelial cells of the homozygous mutant mice. The mutant mice exhibited defects in hemostasis with a highly prolonged bleeding time and spontaneous bleeding events in approximately 10% of neonates. As in the human disease, the factor VIII level in these mice was reduced strongly as a result of the lack of protection provided by vWf. Defective thrombosis in mutant mice was also evident in an in vivo model of vascular injury. In this model, the exteriorized mesentery was superfused with ferric chloride and the accumulation of fluorescently labeled platelets was observed by intravital microscopy. We conclude that these mice very closely mimic severe human von Willebrand disease and will be very useful for investigating the role of vWf in normal physiology and in disease models.

Animals↗

PubMed1998

A system to simulate gas exchange in humans to control quality of metabolic measurements.

We have developed a gas exchange simulation system (GESS) to assess the quality control in measurements of metabolic gas exchange. The GESS simulates human breathing from rest to maximal exercise. It approximates breath-by-breath waveforms, ventilatory output, gas concentrations, temperature and humidity during inspiration and expiration. A programmable motion control driving two syringes allows the ventilation to be set at any tidal volume (VT), respiratory frequency (f), flow waveform and period of inspiration and expiration. The GESS was tested at various combinations of VT (0.5-2.51) and f(10-60 stroke x min(-1)) and at various fractional concentrations of expired oxygen (0.1294-0.1795); and carbon dioxide (0.0210-0.0690) for a pre-set flow waveform and for expired gases at the same temperature and humidity as room air. Expired gases were collected in a polyethylene bag for measurement of volume and gas concentrations. Accuracy was assessed by calculating the absolute and relative errors on parameters (error=measured-predicted). The overall error in the gas exchange values averaged less than 2% for oxygen uptake and carbon dioxide output, which is within the accuracy of the Douglas bag method.

Carbon Dioxide↗

PubMed1998

Effects of bedrest on deltoideus muscle morphology and enzymes.

To examine the effects of unweighting on the structural and metabolic adaptations of a non-postural muscle, deltoideus muscle biopsies were taken in seven male healthy subjects, before and after a 37 day bedrest. Myofibrillar ATPase histochemistry demonstrated no change in fibre type distributions (I, IIA, IIB), in fibre cross-sectional areas nor in capillary supply. No difference was noted in enzyme activities of oxidative metabolism (citrate synthase, 3-hydroxy-acyl-CoA dehydrogenase), and glycolysis (hexokinase, lactate dehydrogenase). Electron microscopy showed a decrease in the volume density of lipids but no change in mitochondrial volume density and distribution. The results indicate that bedrest induces no major morphological and biochemical changes in deltoideus muscle, contrary to what was previously reported in vastus lateralis muscle. This lack of changes is probably related to an unaltered deltoideus muscle use.

3-Hydroxyacyl CoA Dehydrogenases↗

PubMed1998

Validity of oxygen uptake measurements during exercise under moderate hyperoxia.

PURPOSE: The validity of oxygen uptake in hyperoxia (FIO2 = 30%) measured by an automated system (MedGraphics, CPX/D system) was assessed during the simulation of gas exchanges during exercise with a mechanical system and during submaximal exercise by human subjects. METHODS: The simulation system reproduced a stable and accurate VO2 for 30 min (sim-test). This trial was repeated nine times in normoxia and nine times in hyperoxia. Ten subjects also performed two submaximal exercises (55% of normoxic VO2max) on a cycle ergometer at the same absolute power in normoxia and in hyperoxia (ex-test). RESULTS: There was a significant downward drift of the oxygen fraction measurement in hyperoxia (< or = 0.10% for FIO2 and FEO2) during sim-test, but VO2 measurement remained stable in the two conditions. There was also a downward drift of the oxygen fraction measurement in the two conditions (< or = 0.07% for FIO2) during ex-test. VO2 was significantly higher in hyperoxia (+4.6%), and this result was confirmed using a modified Douglas bag method. CONCLUSIONS: These findings show that the CPX/D system is stable and valid for assessing VO2 in moderate hyperoxia.

Adult↗