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Biomedical subjects

B Meyer

Publications and source records attributed to B Meyer.

At least 19 recordsLinked to original sources
PubMed1998

Evidence for IL-12-activated Ca2+ and tyrosine signaling pathways in human neutrophils.

The cytokine IL-12 is proposed to play a bridging role between innate and adaptive immunity. Here we demonstrate that IL-12 binds specifically to human neutrophils. This binding leads to a transient increase in 1) intracellular free calcium due to its release from membrane-enclosed stores and its influx from extracellular medium, 2) actin polymerization, and 3) tyrosine phosphorylation. IL-12 treatment also leads to a concentration-dependent increase in reactive oxygen metabolite production. The effect of IL-12 is blocked by neutralizing Abs to IL-12. Inhibition of either calcium transient or tyrosine phosphorylation causes inhibition of reactive oxygen metabolite production. However, inhibition of actin polymerization enhances IL-12-induced oxidase activation. Our data suggest 1) a direct role for IL-12 in the activation of human neutrophils, and 2) a calcium-dependent signaling pathway for IL-12.

Actins↗
PubMed1998

Spondylodiscitis after lumbar discectomy. Incidence and a proposal for prophylaxis.

STUDY DESIGN: An analysis of the incidence of spondylodiscitis after lumbar disc surgery in 1642 patients. In 508 patients no prophylactic antibiotics were given. In 1134 patients a collagenous sponge containing gentamicin was placed in the cleared disc space. OBJECTIVES: To report the incidence of postoperative spondylodiscitis in cases in which no antibiotic prophylaxis was used, and to define the value of a collagenous sponge containing gentamicin in preventing disc space infections. SUMMARY OF BACKGROUND DATA: Spondylodiscitis is considered to be a rare complication of lumbar disc surgery. The retrospective design of most studies and the rare use of magnetic resonance imaging for early radiologic diagnosis suggest that the reported incidence rates may be underestimates. Postoperative spondylodiscitis is the result of intraoperative contamination and, theoretically, could be prevented by treating these patients with prophylactic antibiotics. METHODS: In 1642 patients, 1712 discectomies were performed. In 508 of these patients no prophylactic antibiotics were given; in 1134 of these patients a collagenous sponge containing gentamicin was placed in the cleared disc space. Clinical reexamination and, in cases of unsatisfactory results, laboratory and radiologic investigations were performed 4-8 weeks after surgery. RESULTS: In nineteen of the 508 patients who were not treated with antibiotic prophylaxis (3.7%) a postoperative spondylodiscitis developed, whereas none of the 1134 patients who received antibiotic prophylaxis became symptomatic (P < 0.00001). CONCLUSION: In the current study, a 3.7% incidence of postoperative spondylodiscitis was found in the absence of prophylactic antibiotics. Gentamicin-containing collagenous sponges placed in the cleared disc space were effective in preventing postoperative spondylodiscitis.

Administration, Topical↗
PubMed1998

Dynamic determination of anaerobic acetate kinetics using membrane mass spectrometry

A small, stirred, 14.4-mL tank reactor was designed to serve as a measurement cell for short-term investigation of microbial kinetics. A mass spectrometer membrane probe allowed the measurement of the dissolved gases of hydrogen, methane, oxygen, and carbon dioxide. pH was measured by an electrode and controlled by addition of acid or alkali. The highly sensitive measurement of gases with low solubility allowed rapid measurements at very low conversion. In kinetic experiments, a stepwise increase of substrate concentration (method A) and continuous feed of substrate (method B) were used, allowing quick estimation of substrate kinetics. Acetate conversion in mixed culture biofilms from a fluidized bed reactor was investigated. Substrate inhibition was found to be negligible in the concentration range studied. Experiments at various pH values showed that the undissociated acid form was the kinetic determinant. Kinetic parameters for Haldane kinetics of protons were KSH = 1.3 x 10(-5) mol m-3 and KIH = 8.1 x 10(-3) mol m-3. With free acid (HAc) as the rate determining species, the kinetic parameters for method A were KSHAc = 0.005 mol m-3 and KIHAc = 100 mol m-3 and for method B were KSHAc = 0.2 mol m-3 and KIHAc = 50 mol m-3. The maximum biomass activity occurred at around pH 6.5. Acetate was exclusively converted to methane and CO2 at pH > 6. Copyright 1998 John Wiley & Sons, Inc.

Journal Article↗
PubMed1998

Symmetric and asymmetric left ventricular hypertrophy in patients with end-stage renal failure on long-term hemodialysis.

BACKGROUND: Patients with end-stage renal disease on regular hemodialysis have an increased prevalence of left ventricular (LV) hypertrophy that is associated with morbidity and mortality. Asymmetric septal hypertrophy and impairment of LV outflow can occur in these patients and may contribute to adverse outcomes. More insight into the prevalence, extent, geometry, and promoting factors of LV hypertrophy is important. METHODS: An unselected group of 62 patients (31 women), aged 55 +/- 14 years, on maintenance hemodialysis was investigated by Doppler echocardiography. Eight patients with valvular heart disease were excluded from further analysis. We assessed prevalence of LV hypertrophy and asymmetric septal hypertrophy, as well as parameters of LV geometry and LV filling and outflow dynamics. RESULTS: Prevalence of LV hypertrophy was 65%. Patients were analyzed according to LV mass and geometry. Mean LV mass index was normal (105 +/- 17 g/m2) in Group 1 without LV hypertrophy (n = 19); it was markedly elevated in Group 2 (symmetric hypertrophy, n = 22) and Group 3 (asymmetric hypertrophy with systolic anterior movement of mitral valve, n = 7), and highest (191 +/- 54 g/m2) in Group 4 (asymmetric hypertrophy without systolic anterior movement of mitral valve, n = 6, p < 0.001). Age, body mass index, and duration of hypertension were associated with LV hypertrophy and asymmetric septal hypertrophy (p = 0.01). Group 3 with systolic anterior motion of mitral valve had the smallest end-diastolic LV diameters (p = 0.02); increased heart rates, and increased ejection velocities in the LV outflow tract (p = 0.03, and p = 0.005, respectively, vs. Groups 1, 2, and 4) which pointed to an impairment of LV outflow. CONCLUSIONS: Symmetric LV hypertrophy and asymmetric septal hypertrophy are frequent in patients on maintenance hemodialysis. Predictors for LV hypertrophy were age and body mass index, and, particularly for asymmetric septal hypertrophy, age and hypertension duration. Volume withdrawal during hemodialysis may lead to symptomatic hypotension due to dynamic obstruction in some patients with severe asymmetric septal hypertrophy.

Adult↗
PubMed1998

Slow-growing labyrinthine masses: contribution of MRI to diagnosis, follow-up and treatment.

We report the use of MRI in the diagnosis, follow-up and therapeutic management of three cases of intralabyrinthine Schwannoma. The diagnosis was based on the history and initial and follow-up MRI findings. The main feature suggesting the diagnosis was a nodular intralabyrinthine mass of low signal intensity on T2-weighted images, and high or isointense signal on T1-weighted images (relative to cerebrospinal fluid), which showed contrast enhancement. Follow-up imaging showed growth of the tumour in one patient. One patient underwent surgery for severe tinnitus. To detect these lesions, MRI should be focussed on the inner ear, using thin-section T2-weighted and T1-weighted images before and after contrast medium. MRI allowed informed surgical planning.

Adult↗
PubMed1998

Alteration of the expression of a plant defensin gene by exon shuffling in bell pepper (Capsicum annuum L.).

We have characterized two members of a gene family encoding defensin-type proteins, j1-1 and j1-2. The structures of these homologous genes are highly similar. Both genes contain an intervening sequence at the same position. Sequence analysis of the intron within the j1-2 gene revealed the existence of an additional exon (exon 2ji) which also encodes a defensin-type protein. It is very likely that this exon was derived by genomic shuffling from a gene, jx, belonging to another subfamily which remains to be characterized. Only transcripts resulting from the splicing of exons 1j2 and 2ji can be detected, indicating that the inserted exon has functionally replaced the original, leaving the latter as a partial pseudogene. This rearrangement did not alter the tissue specificity of expression of the gene j1-2. The corresponding transcripts, present at the stage of fruit set, accumulate progressively during the process of development. In contrast, gene j1-1 is expressed only at the later stages of ripening. Estimates of transcription rates show that in green fruits expression is mainly regulated at a post-transcriptional level, while transcriptional regulation is prominent during ripening.

3' Untranslated Regions↗
PubMed1998

Different response to balloon angioplasty of carotid and coronary arteries: effects on acute platelet deposition and intimal thickening.

PTCA is a well-established intervention to reduce the severity of atherosclerotic coronary stenosis. Its primary success rate is seriously handicapped by the high incidence of late restenosis. Given the clinical and social importance of this proliferative process, new strategies are needed to prevent or reduce restenosis. Several animal models as well as different arteries have been used to study neointimal proliferation after arterial injury. A number of agents have shown to reduce neointimal proliferation after arterial injury in the carotids and iliac arteries of rodent models. Unfortunately, these results have not been replicated in humans. We have compared the acute and late response to vascular injury of the carotid and coronary arteries in the pig. Arterial injury was induced by performing balloon angioplasty of the carotid (elastic) and coronary (muscular) arteries in swine. Acute platelet-thrombus formation was evaluated by quantitation of Indium-labeled platelets deposited on the injured segments 1 h after procedure. Measurement of intimal area was performed by morphometry of the most stenotic cross-section at 28 days after balloon angioplasty. Platelet deposition after mild and severe injury in carotids (4 +/- 1 and 56 +/- 13 x 10(6) platelets/cm2, respectively) and coronaries (15 +/- 5 and 141 +/- 20 x 10(6) platelets/cm2, respectively) are significantly greater in deep, than in mild injury (P < 0.005), and significantly greater in coronary than in carotid arteries after deep injury (P < 0.05). Likewise, late neointima formation was significantly greater (P < 0.05) after mild and severe injury in coronary (17 +/- 0.5 and 56 +/- 2%, respectively) than in carotid arteries (5 +/- 0.5 and 12 +/- 1%, respectively). Acute platelet-thrombus formation and late neointimal thickening are modulated by the degree of injury induced during the interventions; and after disruption of the internal elastic lamina, coronary arteries always had significantly more acute thrombus and neointimal thickening. This study emphasizes the importance of the animal species, the type of injury and the artery chosen for studies on restenosis post interventions.

Acute Disease↗
PubMed1998

Continuous external CSF drainage--a perpetual problem in neurosurgery.

BACKGROUND: Continuous external CSF drainage represents a well established procedure which has been improved by many technical contributions. We present our experience in a prospective study of 212 needle trephinations in 165 consecutive patients with a new screw fixation device. METHODS: The entire procedure is performed at the bedside under local anesthesia with a twist drill. The trephination needle is inserted into the self-tapping cannulated screw fixed to the skull. RESULTS: The mean operation time was 6 min, and the duration of ventricular drainage ranged from 2 h to 44 days. Ninety-one percent (N = 193) of ventricular needles in our series were placed at the first targeting attempt. ICP-monitoring and -therapy (88%) were the main indications for needle trephination in our study. During the study period we observed needle associated complications, such as intracerebral hemorrhages (N = 2, 1%) and infections (N = 17, 8%). CONCLUSIONS: Concerning infection, primary insufficient fixation, and general surgical handling, we found a clear learning curve during the course of our study. In spite of the initial problems at the time of introduction we have to emphasize the outstanding advantages of the new ventriculostomy device: It is a time-saving bedside procedure equipped with an optimum fixation device and it enables uncomplicated exchange of the needle in case of obstruction.

Adolescent↗
PubMed1998

The murine Cdx1 gene product localises to the proliferative compartment in the developing and regenerating intestinal epithelium.

The mouse Cdx1 gene encodes a homeobox-containing transcription factor and is one of the few homeobox genes known to be expressed in endodermally derived tissues of the intestine in fetal and adult mice. A detailed and systematic study of the expression of the Cdx1 protein was carried out during embryonic intestinal development, postnatal cytodifferentiation and in the regenerating (after radiation-induced damage) intestine of the mouse. Using antibodies directed against Cdx1, we show for the first time that the Cdx1 protein is localised in the proliferating immature epithelium during intestinal development. It becomes restricted to the proliferative crypt compartment during postnatal differentiation, as well as in the adult intestine. The mesenchymal layer was completely negative both during embryonic development and in the postnatal intestine. The expression of the protein was first clearly detected throughout the simple columnar epithelium at day 15 of development. This expression progressively became restricted to the regions of epithelial proliferation in the crypts of the adult mouse by day 40 of post-natal development. There were occasional cells that were Cdx1 positive in the villi. During regeneration of the epithelium after radiation-induced damage, Cdx1 expression diminished during the initial phase of cellular regression. The expression was then very strong in the regenerating epithelial foci, but not in the quiescent sterilised crypts between day 4 and 6. The normal pattern was restored between day 6 and 7. The Paneth cells were negative. The physical segregation of Cdx1 with the proliferative compartment and the hierarchy of cell renewal in the intestinal epithelium is an important example of how regulatory genes function in the maintenance and in the dysfunction of renewing tissues.

Animals↗
PubMed1998

Personality correlates of +/- pindolol induced decreases in prolactin.

The present study was conducted to investigate if personality traits can be usefully related to serotonergic vs. dopaminergic action of the 5-HT1a-antagonist +/- pindolol. Forty healthy male volunteers (aged between 20 and 30 years) were randomly assigned to a placebo or a +/- pindolol (30 mg, oral dose) group in a double blind trial. Blood samples were drawn and analyzed for PRL concentrations. In addition, the subjects completed questionnaires on personality. The results indicated that +/- pindolol decreases PRL concentrations depending on personality. While subjects high on impulsivity and related traits (aggression and disinhibition) show lower PRL decreases, well-being and personality traits frequently related to dopaminergic activity were not correlated with changes in PRL. Since reduced (blunted) PRL-responses after 5-HT challenge tests have been reported for impulsives, the present results favor the involvement of primarily serotonergic and probably only secondarily dopaminergic control of +/- pindolol induced PRL decreases.

Adrenergic beta-Antagonists↗
PubMed1998

Physiological steal around AVMs of the brain is not equivalent to cortical ischemia.

To challenge the concept of steal rendering the surrounding cortex ischemic, we examined patterns of nutritive capillary flow in the vicinity of AVMs. With a spectrophotometer (EMPHO, BGT) capillary O2 saturation (O2 satn.) was intraoperatively scanned around AVMs in n = 44 patients and in n = 42 controls. 130,000 O2 satn. values before AVM resection were calculated as medians, ratio of critical values (< 25% O2 satn.), coefficients of variance and compared via ANOVA (p < 0.05). n = 40 AVM patients had no postoperative complication (group A), while in n = 4 cases a hyperperfusion syndrome occurred (group B). Physiological variables were comparable among groups A, B and C (controls). Medians (A: 52.9+/-16.3, B: 44.2+/-17.1, C: 51.9+/-11.5% O2 satn.) and the ratio of critical values (A: 6.5+/-5.1, B: 14.7+/-11.1, C: 7.1+/-4.9 O2 satn.) were identical in groups A and C, but significantly different in group B, indicating exhausted compensation. Decreased flow heterogeneity in group A (A: 20.2+/-12.7, B: 27.9+/-12.4, C: 26.8+/-10.9 O2 satn.) kept median cortical perfusion identical to group C. These results confirm recent findings, that cerebrovascular adaption by capillary recruitment keeps CBF at normal levels in the majority of cases and that chronic noninfarctional cerebral hypoperfusion is eventually the equivalent of steal around AVMs. Only around AVMs predisposed to hemodynamic derangement some areas of local low flow anoxia may exist.

Adult↗
PubMed1998

Functional limitations to daily living tasks in the aged: a focus group analysis.

We assessed constraints on daily living of 59 healthy, active adults 65-88 years of age in focus group interviews. Individual comments about specific problems were coded along the dimensions of (a) the locus of the problem (motor, visual, auditory, cognitive, external, or health limitations); (b) the activity involved (e.g., transportation, leisure, housekeeping); (c) whether the problem was attributable to task difficulty or the perception of risk; and (d) response to limitations (perseverance, cessation, compensation, or self-improvement). The data provide information about the types of difficulties encountered in everyday activities as well as the way in which individuals respond to such difficulties. Each comment was also coded in terms of whether it was remediable via training, design changes, or some combination of the two. More than half of the problems that were reported had the potential to be improved in some way, thus providing direction for future research in human factors and aging. Actual or potential applications of this research include identifying problems and difficulties that older adults encounter in daily activities such as transportation and leisure; more specifically, determining the degree to which such problems are potentially remediable by human factors solutions. Applications of this research also include understanding the types of systems, products, and technologies that older adults interact with currently, or are interested in learning to use.

Activities of Daily Living↗
PubMed1998

[A report of two familial cases of Michel syndrome (bilateral agenesis of the inner ear)].

In two siblings, wearing conventional hearing aid, presenting profound but not total congenital deafness, with no particular antecedents, the imaging destined to confirm the indication of a cochlear implant revealed a total bilateral agenesis of the inner ear. In one of the children, this imaging was confirmed by an exploration of the middle ear performed during a tonsillectomy that was otherwise necessary. We will summarize the literature concerning Michel's Disease, exceptional in its princeps form, and we will discuss the manner of action of conventional devices in these cases which are a priori without any sensorial element.

Adolescent↗
PubMed1998

[Digital multi-filter auditory prosthesis: study of its efficiency in function of number of filters and their programming].

We designed a prototype of a 7-filter digital auditory prosthesis table prototype. For each of these filters frequency band width, amplification and compression were programmable in order to adapt these parameters to the deaf patient's audiometric particularities. We compared the hearing improvement it was possible to obtain either with the 3-analogue-filter auditory prosthesis Triton 3004 from Siemens, or with our prototype as a function of the number of filters (3, 4 or 7) and their frequency band width programmability. We tested 21 patients suffering from middle or severe neurosensory hearing loss. This study allows to demonstrate that to overpass the present analogue T004 device a 7 programmable-width-filter strategy seems to be the most appropriate. Further studies benefiting with material improvement of our prototype and finer audiometric adjustment of filter strategies as well as long term clinical studies have to be carried out.

Acoustic Stimulation↗
PubMed1998

[Cochlear implant and cerebral dominance].

On right handed people the right ear is considered to transmit speech information, and the left ear musical and cognitive information. These dominating ear properties are not exactly symmetrical in the left handed population, and are more consistent in females than in males. CI efficacy assessment is strongly based on speech intelligibility performances, because these criteria allow to measure the social reinsertion and communication possibilities. Consequently, one may ask if the relationship of the implanted side and the patient's handness could not be an important factor of this CI efficacy. We studied this relationship on 71 post-lingually deaf adult implantees. We measured patients handness using the Schachter's version of the so called Edimburg questionnaire described by Geschwind; this measurement has been moderated to take count of ambidextrous and mixed-handed population. Post operative performances has been assessed using the Francophone Protocol devoted to adults. We found that there is no significant correlation between these post-operative performances and the studied relationship. We estimate: 1) This absence of correlation is probably due to the high number of data which lead to determine the ear for implanting. 2) As far as this choice is feasible, dominating ear must nevertheless be elected, not only for theoretical reasons, but because the dominating hand may be easily employed for antenna adjustment. 3) As handness is strongly evident only after 4 y.o., and as left-handness seems to be more frequent on a congenitally deaf population, this choice is more problematic on less than 2 y.o. deaf children.

Cochlear Implantation↗
PubMed1998

[Cochlear implant in the aged patient].

Despite the fact that elderly people live frequently alone and frequently have difficulties of vision, is it reasonable to refuse to supply a patient with a cochlear implant only because he is too old? We compare the results of 87 post-lingually implantees as a function of age, less than 60 years (young) and 60 years or more (old). We assessed the implant efficacy using the Protocole Francophone d'Evaluation (PFE), appreciated the speech-therapist's opinion and the patient's satisfaction, and counted the number of hours per day the implant was used (H/D). The PFE score was significantly higher in young than old. However the speech-therapist's opinion and the patient's satisfaction as well as H/D did not differ significantly in the 2 series. Elderly people are supplied with a great benefit from cochlear implants. Therefore age is not a contraindication for implantation.

Adult↗
PubMed1998

[Indications for the cochlear implant in partial deafness of the adult].

The last (may 1995) NHI Consensus Development Conference on cochlear implant recommends to extend the use of cochlear implant for adult patient suffering from bilateral acquired severe hearing impairment. Its indications are a severe-to-profound sensorineural hearing loss bilaterally presenting an open-set sentence recognition scores less than or equal to 30 percent under best aided conditions. We report the results of our 4 first implantees responding to these criteria, and discuss the mechanisms of the speech intelligibility improvement which has been obtained.

Audiometry, Pure-Tone↗