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Biomedical subjects

J Michel

Publications and source records attributed to J Michel.

At least 37 records · Page 2Linked to original sources
PubMed2001

Optimization of digital filters for the detection of trace elements in EELS. III--Gaussian, homomorphic and adaptive filters.

This paper is the third part of a series of papers dealing with the development of digital filters for the extraction of information from electron energy loss spectra, when the signal-to-background is very weak, as it is the case for elements in weak concentration. Three new filtering approaches are investigated: the use of high-order derivatives (typically, the fourth order derivative of a Gaussian), the use of homomorphic filtering (working on logarithmically-transformed spectra) and the use of adaptive filtering, taking into account the local background shape. These signal processing methods are applied to real spectra to demonstrate and comment their effects in three different cases of signal and background shapes related to calcium, phosphorus and boron detection in definite thickness organic matrix.

Boron↗
PubMed2001

HER-2 and topo-isomerase IIalpha as predictive markers in a population of node-positive breast cancer patients randomly treated with adjuvant CMF or epirubicin plus cyclophosphamide.

BACKGROUND: The predictive role of HER-2 in node-positive breast cancer patients receiving CMF or an anthracycline-based adjuvant therapy remains unclear. In addition, topo-isomerase II alpha (topo IIalpha), as the cellular target of anthracyclines, might have value as a predictive marker. PATIENTS AND METHODS: Four hundred eighty-one archival primary tumor samples were collected among 777 patients entered into a multicenter phase III trial comparing classical CMF with epirubicin cyclophosphamide (HEC) as adjuvant therapy of node-positive breast cancer. HER-2 was evaluated by immunohistochemistry (IHC) using different antibodies (Abs). Topo IIalpha was evaluated by IHC using the Ab KiS 1. In each subgroup of patients identified by HER-2 and topo IIalpha, adjusted hazard ratios for event-free survival (EFS) and the corresponding 95% confidence intervals have been calculated for the different study comparisons. An interaction test has been performed to investigate the role of HER-2 and topo IIalpha as predictive markers. RESULTS: When HER-2 was evaluated by CB-11 and 4D5 mAbs, the EFS adjusted hazard ratios (HR) for the main study comparison HEC vs. CMF were: HER-2 positive: 0.33 (95% confidence interval (95% CI): 0.09 1.27, P = 0.08), HER-2 negative: 1.16 (95%, CI: 0.71-1.90, P = 0.56); the P-value for the interaction test was 0.10. When HER-2 was evaluated by TAB-250 + pAbl Abs, the adjusted HR for the same comparison were: HER-2 positive: 1.06 (95% CI: 0.45-2.52, P = 0.90), HER-2 negative: 0.99 (95% CI: 0.58-1.68, P = 0.97); the P-value for the interaction test was 0.84. With regard to topo IIalpha, the adjusted HR for the EFS comparison HEC vs. CMF were: topo IIalpha positive: 0.66 (95% CI: 0.32-1.36, P = 0.25), topo IIalpha negative: 1.26 (95% CI: 0.63-2.50, P = 0.51); the P-value for the interaction test was 0.13. CONCLUSIONS: This study suggests that in node-positive breast cancer patients randomly treated with CMF or an epirubicin-based regimen, the predictive value of HER-2 may vary according to the Abs used in the immunohistochemistry assay. In addition, the study supports the concept that topo IIalpha might be involved in the determination of tumor responsiveness to an anthracycline-based adjuvant therapy.

Adult↗
PubMed2001

Interleukin-4 polymorphisms in early onset periodontitis.

BACKGROUND, AIMS: Periodontitis is the result of a complex interplay between oral bacteria and the host response, often modulated by behavioral factors. Early-onset periodontitis (EOP) is defined by the age of onset, the distribution of lesions and specific microbial pathogens. METHOD: Studies in twins suggested a genetic contribution to the pathogenesis of periodontitis. EOP heritable factors may be related to immune mechanisms which could enhance the pathogenic potential of plaque bacteria in susceptible individuals. Among others, Interleukin 4 (IL-4) is a potent cytokine in the immune response and is a potent down regulator of macrophage function. In the present study, we report a specific genotype of the IL-4 gene, which was detected by specific primers and PCR analysis. RESULTS: In the EOP-group 27.8% were IL-4 promotor- and intron polymorphism positive (PP+ and IP+). None of the age-matched healthy controls or patients with adult periodontitis (n=25) carried the markers. Moreover, serum IL-4 levels of PP+ and IP+ patients were below the detection limit and significantly different (p<0.01) from the IL-4 concentrations of healthy controls and PP- and IP- patients.

Adult↗
PubMed2001

Inhibition of HIV-1 replication in vitro and in human infected cells by modified antisense oligonucleotides targeting the tRNALys3/RNA initiation complex.

The untranslated 5' leader region of the human immunodeficiency virus type 1 (HIV-1) RNA plays an essential role in retroviral replication. It is the first retrotranscribed RNA region, primed from a cellular tRNALys3 partially annealed to the HIV-1 primer binding site (PBS). The structural and functional features of the HIV-1 reverse transcription initiation complex have been thoroughly studied. In this work, we used chemically modified antisense oligonucleotides (AS-ODN) as competitors of the natural tRNALys3 primer for the PBS region. Modified 2'-O-methyl AS-ODN were able to inhibit in vitro HIV-1 reverse transcription and displace the tRNALys3 previously annealed to the PBS. The destabilization of the initiation complex by 2'-O-methyl ODN was a sequence-specific process. We further demonstrated the importance of an anchor region contiguous to the PBS in the annealing of the antisense molecule, allowing the displacement of tRNALys3. The 20-mer 2'-O-methyl molecules were also able to inhibit viral replication in HIV-1-human infected cells, either by blocking cDNA synthesis during the early phase or by interfering with the annealing of the tRNALys3 primer to the PBS during the late phase of the viral cycle. Thus, the highly conserved retroviral initiation complex was shown to be a promising target when using the antisense strategy.

Base Sequence↗
PubMed2001

[Bifocal avulsion of the patellar tendon in an adult: a case report].

PURPOSE OF THE STUDY: Bifocal proximal and distal avulsion of the patellar tendon is a rare event in adults with, to our knowledge, no previous report in the literature. Exceptional bifocal avulsion of the patellar tendon is generally related to an underlying bone or systemic disease. We report the case of a 90-year-old diabetic patient who developed simultaneous avulsions of the patellar and tibial insertions. CASE REPORT: A 90-year-old woman with noninsulin-dependent diabetes mellitus fell on her left knee and was subsequently unable to extend the knee despite normal quadriceps contraction. Radiographically, the knee joint showed a transverse fracture of the lower third of the patella and a fracture of the anterior tibial tuberosity, evidencing rupture of the quadriceps tendon. Signs of osteoarthritis were minimal. The patient underwent surgery for osteosynthesis of the patella with two vertical pins and a figure-eight wire cerclage in addition to fixation of the anterior tuberosity of the tibia with 3 staples and wire cerclage. The patient recovered well and was walking six months later. DISCUSSION: Bifocal disruption of the extensor system is a rare event in adults. It is usually associated with an underlying bone disease (Paget's disease, osteomalacia, osteitis deformans) or systemic disease (lupus erythematosus, rheumatoid arthritis, hyperparathyroidism, Wilson's disease), but bilateral spontaneous disruption may occur. There have been two reports of patellar full-thickness tendon tears in diabetic patients but no case of a bipolar avulsion involving both insertions. Concurrent forces applied to the ligament were probably the cause of this unique type of patellar tendon avulsion. CONCLUSION: This is the first report of a bifocal disruption of the patellar tendon. Different underlying diseases may be involved. Treatment consists in double fixation.

Accidental Falls↗
PubMed2001

Diagnostic value of vibration-induced nystagmus obtained by combined vibratory stimulation applied to the neck muscles and skull of 300 vertiginous patients.

On subjects with unilateral vestibular dysfunction, the application of a vibratory stimulation (100 Hz) to the two mastoids and the vertex, and to the right and left dorsal neck muscles produces a nystagmus directed towards the good ear in 85% of patients. Fixation must be suppressed by Frenzel's glasses or video nystagmoscopy. To be significant this nystagmus must appear in at least 3 of the 5 vibratory stimulated sites. On healthy subjects nystagmus is present in 6% of cases but never in those below 30 years. In subjects affected by central vertigo, nystagmus was elicited in 10% of cases and in subjects suffering from vertigo of unknown origin in 6% of cases. Vibration nystagmus which stops immediately after stimulation differs from head shaking nystagmus which is present in only 34% of unilateral vestibular dysfunctions. Vibration occasionally produces a pseudo-caloric nystagmus which persists after stimulation. We believe that vibratory stimulation is a useful test, quick and easy to perform. In conjunction with questionnaires, clinical examination, positional testing and the results of audiometry, it gives an immediate indication of a peripheral lesion when the vertigo is seen for the first time. With unilateral deafness, a positive test leads one to suspect an acoustic neuroma. Conversely if the test becomes negative after a vestibular neuritis when it was initially positive, it is a sign of recovery.

Adolescent↗
PubMed2000

Evaluation of immunogenicity and protective efficacy of carrier-free Plasmodium falciparum R23 antigen in pre-exposed saimiri sciureus monkeys.

We have reported previously that the recombinant Glutathione S-transferase GTR23, induced protection after immunisation of naive or previously exposed Saimiri monkeys. We investigated the immunogenicity of carrier-free R23 repeats in pre-exposed animals in two adjuvant formulations. Three of five monkeys immunised with alum-formulated repeats and one of two animals immunised with the Polyalphaolefine formulation produced high titres of cytophilic antibodies with a primary type kinetics, indicating that the anti-P. falciparum antibodies present on the day of challenge were R23-specific. The four responders in R23-specific antibodies were protected against a challenge infection with the virulent FUP/SP strain. The other three animals failed to respond to immunisation and experienced an infection that required drug treatment. Unlike the other three animals that experienced an infection requiring drug treatment. These experiments support further development of the R23 repeats as a vaccine candidate.

Adjuvants, Immunologic↗
PubMed2000

Expression of soluble CD137 correlates with activation-induced cell death of lymphocytes.

CD137 is a member of the tumour necrosis factor receptor family which delivers a potent co-stimulatory signal to T lymphocytes. Soluble forms of CD137 (sCD137) can be found at enhanced levels in sera of patients with rheumatoid arthritis. Here we show that expression of sCD137 lags behind that of membrane-bound CD137 (mCD137) by about 24 h. In fully activated lymphocytes, time of maximum increase and level of expression of sCD137 were at day 2 and 3, respectively. Expression of sCD137 in lymphocytes requires strong activation, and levels of sCD137 correlate negatively with lymphocyte proliferation and positively with the degree of activation-induced cell death caused by mitogen overstimulation. Since activation of lymphocytes through membrane-bound CD137 delivers a potent stimulatory signal, sCD137 may provide a negative control mechanism for immune responses.

Antigens, CD↗
PubMed2000

[Elective laparoscopic colectomy for sigmoid diverticulitis. Prospective study of 56 cases].

OBJECTIVE: The aim of this prospective study was to assess the feasibility and postoperative advantages of the laparoscopic-assisted elective colectomy for diverticular disease. PATIENTS AND METHODS: From january 1989 to december 1997, among the 114 patients electively operated on for diverticulitis, 56 patients were treated by laparoscopic approach. Evaluated parameters included: gender, age, weight, size, ASA score, operating time, duration of hospital stay, of analgesic treatment, and of postoperative ileus, morbidity and mortality rate. RESULTS: The study group consisted of 35 women and 21 men. Mean age was 59 years (34-81 years); 29 patients were ASA 1 and 27 ASA 2. Overall postoperative mortality rate was 0% and morbidity rate 16% (n = 9). There were no complications directly related to laparoscopic technique. The conversion rate was 14% (n = 8). Mean operating time was 300 min (200-600 min). Mean duration of postoperative ileus was 2.4 days. Mean duration of hospital stay was 9.4 days. CONCLUSION: This study demonstrates the feasibility of elective laparoscopic-assisted colonic resection for diverticular disease in more than 80% of cases with a postoperative morbidity and mortality rate comparable to those of conventional surgery.

Adult↗
PubMed2000

Plasmodium falciparumin the squirrel monkey (Saimiri sciureus): infection of non-splenectomised animals as a model for exploring clinical manifestations of malaria.

Plasmodium falciparum infection in humans leads to a variety of symptoms ranging from an influenza-like syndrome to life-threatening complications. Animal models are useful tools for the detailed analysis of the interaction between both parasite and host factors leading to these various clinical manifestations. In this review, examining the different clinical, parasitological and haematological parameters associated with P. falciparum infection in spleen-intact monkeys, we propose this model as a good alternative for exploring some aspects of the host-parasite relationship in malaria.

Anemia↗
PubMed2000

Towards the selection of phosphorothioate aptamers optimizing in vitro selection steps with phosphorothioate nucleotides.

The high affinity of a given nucleic acid for a protein ligand can be used to isolate specific inhibitors of enzymes involved in pathological situations. The latter property is the basis of the SELEX (systematic evolution of ligands by exponential enrichment) technique. Recently, several potent nucleic acids inhibitors of HIV-1 replication have been isolated using the SELEX approach. However, phosphodiester oligodeoxynucleotides (PO-ODNs) were not used as antiviral agents because of their sensitivity to nucleases. Our goal in this work was to explore the possibility of selecting, from a fully substituted phosphorothioate library, oligonucleotides having both a strong affinity for HIV-1 reverse transcriptase (RT) and nuclease resistance. HIV-1 RT initiates in vivo reverse transcription from the 3' end of a host tRNALys. Although phosphorothioate ODNs (PS-ODNs) have been claimed to bind unspecifically to proteins, we have shown previously that an ODN corresponding to the acceptor stem of tRNALys was able to inhibit specifically HIV-1 replication in HIV-1 infected cells, without showing cytotoxicity up to 10 microM. As the SELEX strategy requires 'in vitro' transcription and reverse transcription of the selected DNA, we have assayed the available PS precursors as a model system by using PS-dNTPs and rNTPs. We have also developed an experimental procedure to optimize the incorporation of four PS-dNTPs during the PCR step of the SELEX approach. In the course of this work, we have showed that the PS-dGTP is a strong inhibitor of thermostable DNA polymerases as well as of HIV-1 RT.

Base Sequence↗
PubMed2000

The effects of dietary protein independent of essential amino acids on growth and body composition in genetically lean and fat chickens.

1. Growth performance between 28 and 49 d of age and carcase composition at 49 d in genetically lean (LL) and fat (FL) broilers fed on diets varying in non-essential amino acid (NEAA) concentrations were compared in 2 experiments. In experiment 1, 3 crude protein (CP) contents (133, 155, and 178 g/kg) were compared. In experiment 2, 4 CP levels (131, 150, 170 and 189 g/kg) were compared. All diets were supplemented with synthetic amino acids to cover the EAA requirement of the LL birds. 2. Weight gains of FL chickens were not affected by dietary treatments, while those of LL increased when CP level increased. 3. Reducing CP content always increased body lipids, abdominal fat and food conversion ratio in both lines in both experiments; however, the effect on abdominal fat was more pronounced in the FL birds. 4. Reducing CP concentration always decreased breast muscle proportion in both lines in both experiments, even when growth rate was not affected by CP. 5. It is concluded that LL chickens require diets more concentrated in NEAA than fat chickens and that there seems to be an effect of NEAA on breast muscle development.

Adipose Tissue↗
PubMed2000

Does excess dietary protein improve growth performance and carcass characteristics in heat-exposed chickens?

The effects of two environmental temperatures (22 and 32 C, constant) and five dietary protein contents (10 to 33% CP) were investigated in 4- to 6-wk-old broiler chickens. High ambient temperature reduced growth rate, feed efficiency, and breast muscle proportion and increased abdominal fat proportion. Irrespective of ambient temperature, increasing dietary protein content improved growth performance and carcass characteristics. At 32 C, there was a greater heterogeneity of the data, and bird responses were lower than at 22 C. We concluded that under conditions of chronic heat exposure, diets containing the highest protein levels, 28% and 33% compared with 20% CP, slightly improved chick performance. However, the effect was low and, in our experimental conditions, modifying dietary protein supply (variations in the total quantity of protein) is not sufficient to help broilers to withstand hot conditions.

Animal Husbandry↗
PubMed2000

Cloning and functional expression of the hNPY Y5 receptor in human endometrial cancer (HEC-1B) cells.

Aiming to develop a functional assay for the human NPY Y5 receptor based on adenylyl cyclase activity, HEC-1B cells, in which cAMP synthesis can be efficiently stimulated with forskolin, were selected for the transfection with the pcDNA3-Y5-FLAG and the pcDEF3-Y5 vectors. After optimization of the transfection procedure, the binding of [3H]propionyl-NPY to transiently and stably expressed Y5 receptors was determined. The affinities of NPY, NPY derivatives, and rPP (pNPY > or = p(Leu31Pro34)NPY = p(2-36)NPY > or = p(D-Trp32)NPY > p(13-36)NPY > rPP) were in accordance with the NPY Y5 receptor subtype. For [3H]propionyl-pNPY approximately 1.7 x 10(5) and 1 x 10(6) binding sites per transiently and stably transfected cell, respectively, were determined. The KD values were 2.4 +/- 0.4 and 1.7 +/-0.2 nM, respectively. Due to the high expression of the receptor protein, both stably and transiently transfected cells can be conveniently used in routine radioligand binding studies. By contrast, functional assays were only feasible with HEC-1B cells stably expressing the Y5 receptor. In these cells, 10 nM pNPY inhibited the forskolin-stimulated cAMP synthesis by 75%. This effect was partially antagonized by the Y5 antagonist N-¿trans-[4-(2-naphthylmethylamino)-methyl]cyclohexylmethyl) naphthalene-2-sulfonamide. Although the genetic variability of cancer cells is in principle incompatible with a stable phenotype, both ligand binding characteristics and functionality of the Y5 receptor remained unchanged for more than 30 passages.

Cloning, Molecular↗
PubMed2000

[Treatment of common bile duct stones with laparoscopy. Retrospective multicenter study with 612 patients].

OBJECTIVE: To analyse retrospectively the results of one-stage laparoscopic treatment for common bile duct stones in 19 surgical centers in France. PATIENTS: From January 1991 to July 1996, 612 patients with choledocholithiasis underwent laparoscopic treatment. RESULTS: Overall duct clearance was obtained in 489 of the 612 patients (80%): through the cystic duct in 222 of 380 patients (58.4%), by secondary choledochotomy (after unsuccessful transcystic duct extraction) in 77 of 96 (80%), and in 190 of 232 (82 %) by primary choledochotomy. The overall duct clearance rate increased from 65% in 1991 to 84% in 1996. The use of the choledochotomy approach increased from 43% in 1991 to 69% in 1996 (P<0.01), due to a substantial increase in primary choledochotomy. In contrast, the use of the transcystic approach decreased from 57% to 31% (P<0.01). The mean time for surgery was shorter for cystic duct exploration than for primary choledochotomy (101+/-51 vs. 155+/-62 min, P<0.0001). The mean hospital stay decreased from 7.7+/-3.6 days in 1991 to 4.1+/-2 days in 1996 (P<0.001). The main biliary complications were related to biliary drainage (2,8%) and retained stones (3.1%). CONCLUSION: This study confirms that laparoscopy is a good alternative with a low complication rate, a short hospital stay, and is an effective and safe option for the management of common bile duct stones.

Adolescent↗
PubMed2000

The effect of vanadium-contaminated commercially available albumin solutions on renal tubular function.

We report our findings in a patient with coronary heart disease who received an intravenous albumin solution that contained a significant level of vanadium on the first day after elective primary coronary revascularization. Six patients who underwent similar surgical procedures without albumin infusion were taken as a control group. After administration of the V-contaminated albumin solution, the urinary excretion rates of alpha-glutathione S-transferase, a marker of proximal tubular damage, showed a several-fold elevation above the reference value, and the mean excretion rate was significantly different from that of the control group (p < 0.05). pi-Glutathione S-transferase, a marker of distal tubular damage, only marginally exceeded the upper reference limit in two urine samples from this patient. In all urine samples from the control group the excretion rates of pi-GST were below the detection limit. No significant differences in the excretion rates of alpha1-microglobulin and N-acetyl-beta-D-glucosaminidase were found between the patient treated with the albumin infusion and the patients of the control group. The biological half-life of intravenously administered V was approximately 125 h. All commercially available albumin solutions contain traces of vanadium with the concentration varying between 1.1 and 677 microg/l. The free V fraction in the albumin solutions increased with total V concentration, the highest concentration of free V found being 299 microg/l. The data suggest that the use of albumin solutions containing high levels of vanadium can lead to renal injuries, especially in patients with existing impaired renal function, as is the case with extracorporal circulation. The contamination is believed to be a result of the commercial isolation process.

Albumins↗
PubMed2000

[Semiologic value and optimum stimuli trial during the vibratory test: results of a 3D analysis of nystagmus].

Nystagmus signaling vestibular dysfunction was observed after vibratory stimulation with a 100 Hz ABC stimulator in a population of 36 patients with unilateral labyrinthine pathology (ULP) (pre and postoperative neuromas, vestibular neurectomies) and 10 patients with vestibular neuritis. The stimulus was applied on 3 bony points of the skull (vertex and 2 mastoids) and 2 muscular points of the neck (right and left posterior cervical region). These results were compared with those in 95 normal subjects and 19 cases of central disease and were correlated on the same day with results of the caloric test and head shaking test (HST). A consistent nystagmus was found in only 6 % of the normal subjects (specificity 94 %) and in 10 % of the central lesions, but in 94 % of the 36 peripheral ULP. The sensitivity of the test was equivalent to the HST. The signal was optimized in 30 patients: stimulus frequency, amplitude, stimulator mass, form of the contact, patient tolerance. The best results were obtained for a frequency of 100 Hz and an amplitude of 0.5 mm (there was no response under 0.1 mm vibration amplitude). Under videoscopy and 3D videonystagmography, the direction or side of the nystagmus was constant, but its axis (horizontal, oblique or rotational) changed according to the location of the stimulator: on the mastoid (elective location of stimulation with responses in 94 % of cases) the axis was most often horizontal or horizontal rotational. On the vertex location (where nystagmus was observed in 60 % of cases) the axis of nystagmus was most often rotational or oblique and sometimes horizontal-rotational. The nystagmus showed short latency (less than 200 ms). It started and stopped as stimulation was initiated and interrupted. Nystagmus persisted for the duration of patient tolerance. This nystagmus generally signifies unilateral vestibular weakness rather than vestibular predominance. It is a good indicator of unilateral vestibular dysfunction and could serve as a useful test in clinical practice. We discuss the origin of the nystagmus which may originate in muscle proprioception (by propagation of the vibration to neck muscles) or in the labyrinth (simultaneous excitation of 3 canals on each side).

Adult↗