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Biomedical subjects

F Girard

Publications and source records attributed to F Girard.

At least 55 records · Page 3Linked to original sources
PubMed1999

Dimer initiation sequence of HIV-1Lai genomic RNA: NMR solution structure of the extended duplex.

The genome of all retrovirus consists of two copies of genomic RNA which are noncovalently linked near their 5' end. A sequence localized immediately upstream from the splice donor site inside the HIV-1 psi-RNA region was identified as the domain responsible for the dimerization initiation. It was shown that a kissing complex and a stable dimer are both involved in the HIV-1Lai RNA dimerization process in vitro. The NCp7 protein activates the dimerization by converting a transient loop-loop complex into a more stable dimer. The structure of this transitory loop-loop complex was recently elucidated by Mujeeb et al. In work presented here, we use NMR spectroscopy to determine the stable extended dimer structure formed from a 23 nucleotides RNA fragment, part of the 35 nucleotides SL1 sequence. By heating to 90 degrees C, then slowly cooling this sequence, we were able to show that an extended dimer is formed. We present evidence for the three dimensional structure of this dimer. NMR data yields evidence for a zipper like motif A8A9.A16 existence. This motif enables the surrounding bases to be positioned more closely and permit the G7 and C17 bases to be paired. This is different to other related sequences where only the kissing complex is observed, we suggest that the zipper like motif AA.A could be an important stabilization factor of the extended duplex.

Dimerization↗
PubMed1999

A preliminary study for clinical pharmacokinetics of oral fluorine anticancer medicines using the commercial MRI system 19F-MRS.

These preliminary studies of dynamic natural abundance 19F-magnetic resonance spectroscopy (19F-MRS) on 5-FU based medicines were performed in the human liver using commercial 1.5 T MRI equipment. A single tuned, custom-made circular shape surface coil with a diameter of 15 cm operating at 60 MHz was used for the 19F-MRS study. Localized proton shimming with a whole body coil was performed with adequate volume to include the observing area of the surface coil, and the line width of the water signal was less than 40 Hz. Very different spectroscopic appearance patterns of 5-FU were observed. We examined whether the pharmacokinetics in the liver of orally administered 1-hexylcarbamoyl-5-fluorouracil (HCFU) differ from those of orally administered 5'-deoxy-5-fluorouridine (5'-DFUR). This preliminary study suggested the 19F-MRS technique could be a useful method of evaluating in vivo the metabolism of 5-FU based medicines.

Administration, Oral↗
PubMed1999

[Cerebral ischemic accidents in young subjects. A prospective study of 296 patients aged 16 to 45 years].

From 1990 to 1997, June, 296 patients (156 males and 140 females), aged 16 to 45 years, admitted in the Neurology Department of the University Hospital of Nancy (F) for ischemic stroke, were prospectively evaluated according to a standardized analysis of anamnestic and clinical data, angiography (90 p. 100 of cases), TEE (78 p. 100), hemostasis. Women were younger (mean age = 34.82 y) than men (36.87 y; p = 0.003), with a peak in the 4th decade. Clinical event was a TIA in 14.2 p. 100, a stroke in 51.7 p. 100; it concerned the anterior circulation in 64.5 p. 100, posterior circulation in 25 p. 100, multiple territories in 10.5 p. 100. History of TIA, cervical-cranial pain or Horner syndrome suggestive of dissection, pregnancy or post-partum were found respectively in 60 (20.3 p. 100), 34 (11.1 p. 100) and 13 (9.3 p. 100) cases. Risk factors concerned 87.2 p. 100 of patients, mainly smoking (55.1 p. 100), oral contraceptive (53 p. 100), hyperlipemia (35 p. 100), and were more frequent in case of atheroma and lacunar stroke (p < 0.0000). Etiology, according to TOAST classification, was: atheroma (8.4 p. 100), cardioembolism (8.7 p. 100), small-artery disease (7.1 p. 100), dissection (15.5 p. 100), other determined causes (11.1 p. 100), multiple causes (5.7 p. 100), undetermined cause (34.8 p. 100). Septal pathology was found 34 times. Patients whose stroke remained unexplained were younger (33.7 y vs 37.7, p = 0.002), had less risk factors (p < 0.0000), had more TIA (p = 0.005), more often in the carotid territory (p = 0.008), had a better prognosis (p = 0.01), and showed more often emboli at angiography (p = 0.001). During a mean follow-up of 33 months (median = 19), 21 recurrent strokes occurred and 6 patients died. 134 (46 p. 100) patients had no sequelae, 101 (34.7 p. 100) minor disability, 42 (14.4 p. 100) major sequelae. These results, compared to the main studies of the literature, suggest the interest of common definition criteria and classification of etiologies. In practice, hierarchisation of investigations may be proposed, and vascular risk factors should be tracked in young patients. In patients whose stroke remains unexplained, further studies, as atrial vulnerability, are needed.

Adolescent↗
PubMed1998

In vivo analysis of scaffold-associated regions in Drosophila: a synthetic high-affinity SAR binding protein suppresses position effect variegation.

Scaffold-associated regions (SARs) were studied in Drosophila melanogaster by expressing a synthetic, high-affinity SAR-binding protein called MATH (multi-AT-hook), which consists of reiterated AT-hook peptide motifs; each motif is known to recognize a wide variety of short AT-rich sequences. MATH proteins were expressed specifically in the larval eye imaginal discs by means of the tetracycline-regulated transactivation system and tested for their effect on position effect variegation (PEV). MATH20, a highly potent SAR ligand consisting of 20 AT-hooks, was found to suppress whitemottled 4 variegation. This suppression required MATH20 expression at an early larval developmental stage. Our data suggest an involvement of the high AT-rich SARs in higher order chromatin structure and gene expression.

Animals↗
PubMed1998

Growth hormone therapy with three dosage regimens in children with idiopathic short stature. European Study Group Participating Investigators.

OBJECTIVE: In children with idiopathic short stature (ISS) we studied the growth-promoting effect at 4 years of recombinant human growth hormone (rhGH) therapy in three dose regimens and evaluated whether increasing the dosage after the first year could prevent a decline in height velocity (HV). DESIGN: Included were 223 patients who were treated with subcutaneous administrations of rhGH 6 days per week. They were randomized to three groups: 3 IU/m2 body surface/day, 4.5 IU/m2/day, and 3 IU/m2/day during the first year and 4.5 IU/m2/day thereafter, corresponding with dosages of 0.2 and 0.3 mg/kg body weight/week, respectively. Growth was compared with a standard of 229 untreated children with ISS [ISS standard]. RESULTS: During the first year of treatment HV almost doubled and was higher with 4.5 IU/m2 than with 3 IU/m2. In the second year HV no longer differed among the groups, but increasing the dosage slowed the rate of the fall of HV. During 4 years of therapy the height SD score for age increased by a mean (SD) of 2.5 (1.0) [ISS standards], or 1.2 (0.7) (British standards), bone age increased by 4.8 (1.3) years, and predicted adult height SD score increased by 1.5 (0.7). After 4 years the results of the group with 4.5 IU/m2 were slightly better than those of the other groups. When dropouts were included in the analysis (assuming a stable height SD score after discontinuation of rhGH therapy), height gain was still significant. CONCLUSIONS: During 4 years of rhGH therapy, growth and final height prognosis improved, slightly more with 4.5 IU/m2 than with 3 IU/m2 or 3 to 4.5 IU/m2. However, bone age advanced on average 4.8 years during this period; therefore, any effect on final height will probably be modest.

Body Height↗
PubMed1998

Estimation of the pulmonary capillary wedge pressure from transesophageal pulsed Doppler echocardiography of pulmonary venous flow: influence of the respiratory cycle during mechanical ventilation.

OBJECTIVE: Pulsed Doppler measurement of pulmonary venous flow (PVF) in the left superior pulmonary vein has been suggested as a noninvasive method to evaluate pulmonary capillary wedge pressure (PCWP). In previous studies, PVF was measured at end-expiration, and it is unknown to what extent PVF is affected by the respiratory cycle. It is hypothesized that phasic variations of PVF during mechanical ventilation may be used to estimate PCWP. DESIGN: Prospective clinical study. SETTING: Tertiary care university hospital. PARTICIPANTS: Thirty patients undergoing elective cardiac surgery. INTERVENTIONS: At multiple intervals during the surgery, the PVF was measured with transesophageal pulsed Doppler echocardiography, and measurements of PCWP and airway pressure were simultaneously obtained. MEASUREMENTS AND RESULTS: Components of PVF evaluated were the systolic (X), diastolic (Y), and atrial (Z) waves with their velocity-time integrals (VTI). The systolic fraction (SF = VTI X/[VTI X + VTI Y]) and respiratory variations of each component of PVF were determined and compared with PCWP. There was a greater respiratory variation of the X wave (X expiratory-X inspiratory/X expiratory) in patients with PCWP < 18 mmHg than in patients with PCWP > or = 18 mmHg (0.19 +/- 0.19 v 0.14 +/- 0.13, respectively, p < 0.01). PVF components measured at end-expiration that related best with PCWP were the X/Y peak velocities (r = -0.53), VTI X/VTI Y ratio (r = -0.42), and the SF (r = -0.49). When measured during end-inspiration, the relation of the X/Y ratio, VTI X/VTI Y, and SF with the PCWP were r = -0.54, r = -0.41, and r = -0.50, respectively. CONCLUSIONS: It has been documented that PVF velocity is influenced by the respiratory cycle during mechanical ventilation in patients undergoing cardiac surgery, and the magnitude of this variation is influenced by PCWP. However, it is not actually possible to predict PCWP accurately using these findings. Further studies are needed in which preload is varied acutely to confirm the usefulness of the results.

Adult↗
PubMed1997

Genetic factors regulate processes related to anxiety in mice.

The propensity for anxiety-related behavior has been studied by comparing two highly inbred strains of mice, ABP/Le and C57BL/6ByJ, in two behavioral procedures, open-field and light-dark preference. Their Mendelian F2 population allowed us to evaluate the putative involvement of four easily identifiable loci in anxiogenic processes. In fact, chromosomal regions containing the brown, pink-eyed dilution and short-ear loci on the 4th, 7th and 9th chromosomes respectively are associated with anxiety-related behavior patterns. In addition, binding of [3H]flumazenil to brain GABA(A) receptors was measured as a biochemical index that may be associated with observed behavior patterns.

Animals↗
PubMed1997

Haemodynamic effects of mechanical peritoneal retraction during laparoscopic cholecystectomy.

PURPOSE: Abdominal wall retraction (AWR) was recently proposed as an alternative for CO2 pneumoperitoneum. In this study we evaluated the cardiorespiratory effects of AWR during laparoscopic cholecystectomy. METHODS: Fifteen patients were studied during laparoscopic cholecystectomy using AWR. Monitoring included heart rate (HR), mean arterial pressure (MAP), pulse oxymetry (SpO2), end-tidal CO2 (PETCO2) minute ventilation, and peak inspiratory pressure (PIP). Using transoesophageal echocardiography, the transgastric short axis view was obtained to derive the end-diastolic area (EDA), the end-systolic area (ESA), and the ejection fraction (EF). These parameters were measured at predetermined periods: 1) five minutes after anaesthetic induction, 2) five minutes after AWR insertion, 3) 15 min after AWR insertion, and 4) after the end of surgery. RESULTS: No change in any measured parameter was observed over time in the AWR group except for an increase in MAP (P < 0.05) after AWR insertion. There were no changes in EDA, ESA and EF during the study, reflecting stable global cardiac function. In addition, no embolic episodes were observed during surgery. CONCLUSION: Our results demonstrate that the use of gasless abdominal distention for laparoscopic cholecystectomy results in a stable haemodynamic profile in healthy patients without cardiac disease, except for a brief increase in MAP after the AWR insertion. The advantages of AWR over conventional pneumoperitoneum should be confirmed in higher risk patients in a prospective, randomized study.

Adult↗
PubMed1997

Kinetics of specific immunoglobulin A, M and G production in the duodenal and caecal mucosa of chickens infected with Eimeria acervulina or Eimeria tenella.

The development and appearance of antibody was studied in the intestine and serum from histocompatible GB1 chickens orally infected with oocysts of Eimeria acervulina (restricted to the duodenum) or Eimeria tenella (restricted to the caeca). The local immune response was measured as the specific antibody levels in the supernatants of intestinal fragments (duodenum and caecum) maintained in culture for 16 h at 41 degrees C, 5% CO2, 95% air. Specific IgM was detected 1 week after E. acervulina infection, and the specific IgA and IgG contents of the duodenum and caecum were significantly elevated (P < 0.001) after 2 weeks. The intestinal specific IgG content was raised. E. tenella infection resulted in specific IgA only in the parasitized area during the second week post-infection (P < 0.05). Specific IgM and IgG were both detected in the duodenum and caecum, respectively, 1 and 2 weeks p.i. Production of parasite-specific immunoglobulins was always significantly higher in the parasitized than in the unparasitized areas (caeca for E. acervulina, duodenum for E. tenella). This ex vivo culture assay of intestinal fragments used to measure the mucosal immune response of intestinal areas showed a significant production of specific IgA and IgM. In addition, high levels of IgG were also measured. The role of this specific IgG in Eimeria infection remains to be determined.

Animals↗
PubMed1997

Neuromuscular blockade with acute respiratory failure in a patient receiving cibenzoline.

Cibenzoline is a class Ic antiarrhythmic agent that can be used to treat supraventricular arrhythmias. A case is reported of cibenzoline overdose in a patient with impaired renal function, leading not only to the usual cardiac and metabolic symptoms (bradycardia and hypoglycaemia), but also to a myastheniform syndrome with acute respiratory failure. Neuromuscular blockade was demonstrated by repetitive supramaximal stimulation of the median nerve, and diaphragmatic involvement was evidenced by applying the same protocol to the phrenic nerve. Muscle strength recovered as serum cibenzoline levels decreased, allowing the patient to be weaned from the ventilator. This observation suggests that cibenzoline, like other antiarrhythmic agents, can be responsible for neuromuscular blockade, and should therefore be used with caution in patients with neuromuscular and respiratory diseases or with impaired renal function.

Acute Disease↗
PubMed1997

The cramped gene of Drosophila is a member of the Polycomb-group, and interacts with mus209, the gene encoding Proliferating Cell Nuclear Antigen.

We have isolated and molecularly characterized the cramped (crm) gene of Drosophila melanogaster, and show that it can be classified as a Polycomb-group (Pc-G) gene. crm mutants exhibit typical Pc-G mutant phenotypes, reminiscent of ectopic homeotic gene expression, with additional sex comb teeth found on mesothoracic and metathoracic legs, and proximodistal transformations of the tarsal segments. crm encodes an 693 amino acids protein, with no significant homology to known proteins. We used polyclonal antibodies raised against bacterially expressed truncated CRM protein to show that the crm gene product is localized to the nucleus during embryogenesis. This nuclear localization appears to be restricted to S-phase nuclei, as CRM immunostaining disappears at mitosis. We found that this cell-cycle-dependent staining pattern was identical to that of Proliferating Cell Nuclear Antigen (PCNA). Furthermore, we provide evidence for co-localization of CRM and PCNA proteins in salivary gland polytene nuclei, and for a genetic interaction between crm and mus209, the Drosophila gene encoding PCNA. Together, our data suggest that these two proteins are involved in a common regulatory pathway and highlight possible interactions between Pc-G-mediated silencing and DNA replication in Drosophila.

Amino Acid Sequence↗
PubMed1995

Nuclear localization of the testis determining gene product SRY.

We have studied the expression of the human SRY protein (termed p27SRY) in two different cell lines by using specific antibodies. Confocal microscopy enabled us to localize p27SRY precisely in the nucleus in a discrete punctuate pattern. Furthermore, through microinjection experiments, we have demonstrated that the localization of the p27SRY protein into the nucleus was an event involving the NH2-terminal part of the high mobility group (HMG) domain. With the help of several synthetic peptides and various p27SRY mutants, we have characterized a bipartite basic motif in this part of the protein corresponding to a nuclear localization signal. This nuclear localization signal appears to be highly conserved in SRY box- and HMB box-containing proteins, suggesting common properties of nuclear targeting within the HMG box protein family.

Amino Acid Sequence↗
PubMed1995

The serum response factor nuclear localization signal: general implications for cyclic AMP-dependent protein kinase activity in control of nuclear translocation.

We have identified a basic sequence in the N-terminal region of the 67-kDa serum response factor (p67SRF or SRF) responsible for its nuclear localization. A peptide containing this nuclear localization signal (NLS) translocates rabbit immunoglobulin G (IgG) into the nucleus as efficiently as a peptide encoding the simian virus 40 NLS. This effect is abolished by substituting any two of the four basic residues in this NLS. Overexpression of a modified form of SRF in which these basic residues have been mutated confirms the absolute requirement for this sequence, and not the other basic amino acid sequences adjacent to it, in the nuclear localization of SRF. Since this NLS is in close proximity to potential phosphorylation sites for the cAMP-dependent protein kinase (A-kinase), we further investigated if A-kinase plays a role in the nuclear location of SRF. The nuclear transport of SRF proteins requires basal A-kinase activity, since inhibition of A-kinase by using either the specific inhibitory peptide PKIm or type II regulatory subunits (RII) completely prevents the nuclear localization of plasmid-expressed tagged SRF or an SRF-NLS-IgG conjugate. Direct phosphorylation of SRF by A-kinase can be discounted in this effect, since mutation of the putative phosphorylation sites in either the NLS peptide or the encoded full-length SRF protein had no effect on nuclear transport of the mutants. Finally, in support of an implication of A-kinase-dependent phosphorylation in a more general mechanism affecting nuclear import, we show that the nuclear transport of a simian virus 40-NLS-conjugated IgG or purified cyclin A protein is also blocked by inhibition of A-kinase, even though neither contains any potential sites for phosphorylation by A-kinase or can be phosphorylated by A-kinase in vitro.

Amino Acid Sequence↗
PubMed1995

Delayed cyclin A and B1 degradation in non-transformed mammalian cells.

Cyclins A and B are known to exhibit significant differences in their function, cellular distribution and timing of degradation at mitosis. On the basis of observations in marine invertebrates and Xenopus, it was proposed that cyclin destruction triggers cdc2 kinase inactivation and anaphase onset. However, this model has recently been questioned, both in Xenopus and in budding yeast. In this report, we present evidence for delayed degradation of both cyclins A and B1 in non-transformed mammalian cells. Indeed, by means of indirect immunofluorescence and confocal microscopy, we show that cyclins A and B1 are present up to anaphase in REF52, Hs68, human primary fibroblasts and NRK epithelial cells. In marked contrast, cyclin A is shown to be degraded within metaphase and cyclin B just at the transition to anaphase in HeLa and two transformed cell lines, derivatives of normal NRK and REF52. These results further support the notion that cyclin destruction might be not correlated with anaphase onset in normal cells and highlight a significant difference in the fate of mitotic cyclins between transformed and non-transformed cells.

Animals↗