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Biomedical subjects

G Meyer

Publications and source records attributed to G Meyer.

At least 127 records · Page 7Linked to original sources
PubMed2000

[Acute circulatory failure caused by primary pulmonary hypertension or pulmonary embolism].

Patients with acute massive pulmonary embolism or primary pulmonary hypertension may develop acute circulatory failure and are therefore admitted in the intensive care. The mortality rate of patients with pulmonary embolism and shock varies between 25 and 35% whereas the corresponding figure in patients with submassive embolism is less than 10%. Spiral computed tomography may be the most convenient test for diagnosing pulmonary embolism in the setting of acute circulatory failure. In the few patients who remain unstable despite adequate symptomatic treatment, transthoracic echocardiography combined with clinical judgement is appropriate. Inotropic support and thrombolytic therapy are clearly indicated for patients with massive embolism and shock. The role of the latter is more controversial in patients with right ventricular distension and normal blood pressure. The optimal duration of anticoagulant therapy for pulmonary embolism remains to be defined. Most patients are adequately treated with a six-month course of oral anticoagulants. A shorter duration may be sufficient when a transient risk factor is the cause of the initial event whereas patients with cancer or antithrombin deficiency may require a life long treatment. Primary pulmonary hypertension is a much more uncommon disease which can also lead to right ventricular failure. Symptomatic treatment combines oxygen, inotropic drugs, as well as the optimisation of right ventricular filling pressure. Specific treatment includes inhaled nitric oxide or intravenous epoprostenol followed by anticoagulants with either calcium channel blockers in patients responding acutely to vasodilators or a continuous infusion of epoprostenol in those who do not respond to acute challenge or who are not improving with calcium channel blockers. Although the long term survival has markedly improved as a result of epoprostenol treatment, some patients with refractory primary pulmonary hypertension remain candidates for lung transplantation.

Acute Disease↗
PubMed2000

Markers of hemostatic system activation in pulmonary embolism. Changes during and after cessation of anticoagulant treatment.

Plasma levels of prothrombin fragment 1+2 (Fl+2), thrombin-antithrombin complexes (TAT) and D-dimers were measured in 15 patients with pulmonary embolism during heparin therapy, oral anticoagulation, and after cessation of warfarin therapy. Each patient had a favorable outcome during anticoagulant therapy (3 months), but late venous thromboembolism occurred in six cases. The mean levels of the three markers were significantly increased on day 4 after the thrombotic event, and normalized during warfarin therapy. Nine months after the initial pulmonary embolism, mean levels of the three markers, as compared with a control population, were significantly higher in the patients with late recurrences, whereas only TAT were slightly higher in patients without recurrences as compared with controls. Only TAT levels were significantly higher in the patients with late recurrences than in those without late recurrences. Thus, the levels of the three markers 9 months after pulmonary embolism seem to be interesting to identify patients with high risk of recurrence and who might require longer anticoagulant treatment.

Adult↗
PubMed2000

Discrimination between neoplastic and nonneoplastic brain lesions by use of proton MR spectroscopy: the limits of accuracy with a logistic regression model.

BACKGROUND AND PURPOSE: The most accurate method of clinical MR spectroscopy (MRS) interpretation remains an open question. We sought to construct a logistic regression (LR) pattern recognition model for the discrimination of neoplastic from nonneoplastic brain lesions with MR imaging-guided single-voxel proton MRS data. We compared the LR sensitivity, specificity, and receiver operator characteristic (ROC) curve area (Az) with the sensitivity and specificity of blinded and unblinded qualitative MRS interpretations and a choline (Cho)/N-acetylaspartate (NAA) amplitude ratio criterion. METHODS: Consecutive patients with suspected brain neoplasms or recurrent neoplasia referred for MRS were enrolled once final diagnoses were established by histopathologic examination or serial neurologic examinations, laboratory data, and imaging studies. Control spectra from healthy adult volunteers were included. An LR model was constructed with 10 input variables, including seven metabolite resonance amplitudes, unsuppressed brain water content, water line width, and the final diagnosis (neoplasm versus nonneoplasm). The LR model output was the probability of tumor, for which a cutoff value was chosen to obtain comparable sensitivity and specificity. The LR sensitivity and specificity were compared with those of qualitative blinded interpretations from two readers (designated A and B), qualitative unblinded interpretations (in aggregate) from a group of five staff neuroradiologists and a spectroscopist, and a quantitative Cho/NAA amplitude ratio > 1 threshold for tumor. Sensitivities and specificities for each method were compared with McNemar's chi square analysis for binary tests and matched data with a significance level of 5%. ROC analyses were performed where possible, and Az values were compared with Metz's method (CORROC2) with a 5% significance level. RESULTS: Of the 99 cases enrolled, 86 had neoplasms and 13 had nonneoplastic diagnoses. The discrimination of neoplastic from control spectra was trivial with the LR, reflecting high homogeneity among the control spectra. An LR cutoff probability for tumor of 0.8 yielded a specificity of 87%, a comparable sensitivity of 85%, and an area under the ROC curve of 0.96. Sensitivities, specificities, and ROC areas (where available) for the other methods were, on average, 82%, 74%, and 0.82, respectively, for readers A and B, 89% (sensitivity) and 92% (specificity) for the group of unblinded readers, and 79% (sensitivity), 77% (specificity), and 0.84 (Az) for the Cho/NAA > 1 criterion. McNemar's analysis yielded significant differences in sensitivity (n approximately 86 neoplasms) between the LR and reader A, and between the LR and the Cho/NAA > 1 criterion. The differences in specificity between the LR and all other methods were not significant (n approximately 13 nonneoplasms). Metz's analysis revealed a significant difference in Az between the LR and the Cho/NAA ratio criterion.

Adolescent↗
PubMed2000

Increased apoptosis in acquired sideroblastic anaemia.

Idiopathic acquired sideroblastic anaemias (IASAs) form a subgroup of the myelodysplastic syndromes and are characterized by mitochondrial iron accumulation, bone marrow erythroid hyperplasia and decreased peripheral red blood cell counts. Increased intramedullary apoptosis of erythroid precursors is presumed to constitute the pathophysiological mechanism explaining this ineffective erythropoiesis, but if and how mitochondrial dysfunction is implicated in this process is currently unknown. We therefore studied bone marrow precursor cells obtained from nine patients with IASA for (i) caspase 3 activity, (ii) numbers of Annexin V- and 7-amino-actinomycin-positive cells, (iii) numbers of cells with diminished mitochondrial membrane potential, Delta Psi(m), and (iv) numbers of cells producing reactive oxygen species (ROS), and we compared the results with those of five normal bone marrow samples. Compared with controls, we found increased caspase 3 activity in all IASA samples, which correlated with increased numbers of Annexin-V-positive cells (r = 0.7). Analysis of different subpopulations showed increased apoptosis in erythroid populations compared with myeloid and/or lymphoid populations in five out of nine cases, and increased apoptosis in the last two populations in four out of nine cases. As evidence of mitochondrial dysfunction, Delta Psi(m) was found to be diminished in the erythroid subpopulations of all cases of IASA (66.6 +/- 17% vs. 34.6 +/- 12% in normals). Delta Psi(m) decrease was correlated to Annexin V positivity (r = 0.7). Astonishingly, no difference was found between IASA and normal bone marrows with regard to the number of ROS-producing cells. In fact, both groups exhibited a similar low proportion of ROS production (10.3 +/- 7% in normals vs. 6.8 +/- 5% in IASA). Taken together, our results show that mitochondria are clearly implicated in the apoptotic process in IASA patients. Whether this is a result of an intramitochondrial defect (e.g. Fe accumulation, secondary to mitochondrial or nuclear DNA mutations) or is secondary to an extracellular stimulus [e.g. tumour necrosis factor (TNF), Fas ligand (FasL)] remains to be determined.

Adult↗
PubMed1999

Reelin expression during embryonic brain development in lacertilian lizards.

The expression of reelin mRNA and protein was studied during embryonic brain development in the lacertilian lizards L. viridis and L. galloti, by using radioactive in situ hybridization and immunohistochemistry. At all stages studied, high reelin expression was consistently found in the olfactory bulb, in the lateral cortex, and in neurons of the marginal zone and subplate of medial and dorsal cortical sectors. In the dorsal ventricular ridge (DVR), reelin expression was confined to deeply located, large cells which were more abundant in the caudal than the rostral part of the DVR. In the diencephalon, the ventral lateral geniculate complex and the perirotundal were strongly positive, whereas other nuclei were mostly negative. High reelin signal was associated with some layers in the tectum, with the torus semicircularis, cerebellar granule cell layers, and the ventral horn of the spinal cord. A more moderate signal was detected in the septal nuclei, striatum, retina, habenular nuclei, preoptic and periventricular hypothalamic components, and in reticular nuclei of the mid- and hindbrain. The medial and dorsal cortical plate and Purkinje cells were reelin-negative but expressed disabled-1 (Dab1) mRNA. When they are compared with reelin expression during mammalian brain development, our data reveal an evolutionarily conserved canvas of reelin expression, as well as significant differences, particularly in developing cortical fields. The developing lizard cortex differs from that of turtles, birds, crocodiles, and mammals in that it displays heavy reelin expression not only in neurons of the marginal zone that might be homologous to mammalian Cajal-Retzius cells, but also in subplate neurons. This difference in the pattern of reelin expression suggests that the elaborate radial organization of the lacertilian cortical plate, somewhat reminiscent of its mammalian counterpart, results from evolutionary convergence. Our data lend support to the hypothesis that the reelin signaling pathway played a significant role during cortical evolution.

Animals↗
PubMed1999

Antibody response to glycoprotein E after bovine herpesvirus type 1 infection in passively immunised, glycoprotein E-negative calves.

This study was conducted to determine whether young calves with maternal antibodies against bovine herpesvirus type 1 (BHV-1) but without antibodies against glycoprotein E (gE) can produce an active antibody response to gE after a BHV-1 infection. Five calves received at birth colostrum from gE-seronegative cows which had been vaccinated two or three times with an inactivated BHV-1, gE-deleted marker vaccine. After inoculation with a wild-type virulent strain of BHV-1, all the passively immunised gE-negative calves shed virus in large amounts in their nasal secretions. All the calves seroconverted to gE within two to four weeks after inoculation and then had high levels of gE antibodies for at least four months. The development of an active cell-mediated immune response was also detected by in vitro BHV-1-specific interferon-gamma assays. All the calves were latently infected, because one of them re-excreted the virus spontaneously and the other four did so after being treated with dexamethasone. The results showed that under the conditions of this work the gE-negative marker could also distinguish between passively immunised and latently infected calves.

Animals↗
PubMed1999

[Experience with the transabdominal preperitoneal (TAPP) technique regarding recurrent hernia].

INTRODUCTION: It was our aim to evaluate the results of laparoscopic transabdominal preperitoneal hernia repair (TAPP) with regard to recurrent hernias treated in our department. METHODS: Included were 276 operations for first or subsequent recurrence of inguinal hernia previously treated with suture repair. All final repairs were carried out using the TAPP technique. The data were collected prospectively. The patients were examined 2 weeks and 1 year postoperatively. The rate of follow-up amounted to 78.1 % at 1 year after operation. RESULTS: Perioperative complications were monitored prospectively and divided into intraoperative, minor and major. The overall complication rate amounted to 9 %, major complications 5.3 %. The re-recurrence rate was 0.4 %. CONCLUSIONS: Because of the general advantages of laparoscopic surgery and the low recurrence rate we prefer laparoscopic hernioplasty using the TAPP technique.

Adult↗
PubMed1999

[Laparoscopic treatment of Morgagni-Larrey hernias].

Three patients with Morgagni-Larrey hernias are reported who underwent successful laparoscopic repair between 1992 and 1998. The hernia was closed by direct suturing in one case; in the two other cases a polypropylene mesh was used because of the size of the hernia in one case and in the other because of muscle atrophy in a patient with Charcot-Marie-Tooth disease. There were no complications, and the patients were discharged 3-4 days after surgical treatment. The current follow-up is between 10 months and 6 years; there have been no hernia recurrences and all patients are asymptomatic. We consider laparoscopic repair to be a suitable and safe procedure for treatment of Morgagni hernias. We discuss the two different techniques, direct suturing or using polypropylene mesh by reviewing the results of the current literature.

Adult↗
PubMed1999

Deoxycholic acid is not related to lithogenic factors in gallbladder bile.

The influence of deoxycholic acid (DCA) on the factors in gallbladder bile responsible for cholesterol gallstone disease has been a controversial subject of discussion. This might be partially due to patient selection or inappropriate methods. Therefore, we investigated the relationship between the percentage of DCA and lithogenic factors in the gallbladder bile of patients with cholesterol gallstones and with normal or moderately impaired gallbladder contractility. Patients with pigment stones served as a control group. The percentage of DCA in the gallbladder bile of 20 patients with cholesterol stones (23.2%+/-6.5%; mean+/-SD) was comparable to the DCA percentage in the gallbladder bile of 11 patients with pigment stones (26.5%+/-8.5%). No correlation was seen between the DCA percentage of total bile acids and the crystal observation time, cholesterol saturation index (CSI), total protein value, mucin level, and amount of cholesterol in vesicles or crystals in the total group of patients or in the subgroups with cholesterol or pigment stones, respectively. The lack of correlation between DCA percentage and CSI was determined in native bile (r = 0.048) as well as in crystal-free bile after ultracentrifugation (r = 0.107). Our findings demonstrate that in patients with gallstones, the percentage of DCA in gallbladder bile is not related to any of the known biliary factors associated with cholesterol gallstone disease. We conclude that in patients with normal or moderately impaired gallbladder function, an elevated DCA level in the gallbladder bile is of minor pathophysiologic significance for the formation of cholesterol gallstones.

Adult↗
PubMed1999

Craniomandibular disorders--comparative investigations with clinical examination and electronic axiography.

An essential problem in the diagnosis of craniomandibular disorders is still the evaluation of the type and severity of the TMJ diseases. For a differential classification of TMJ diseases, we developed an electronic axiography system which facilitates a recording of lower jaw movements. It works 3-dimensionally and relates to the joints. The measuring system, which was internationally patented, is based on a linear resistive foil for the sagittal plane and an inductive gauge for the horizontal plane. The aim of this pilot study was to evaluate the usefulness of our electronic axiography system in obtaining a differential diagnosis of craniomandibular disorders. We examined 30 patients (60 joints) with complaints in the TMJ area (pain and TMJ sounds). Clinical examinations yielded only uncertain indications of TMJ disease. With the help of electronic axiography we could differentiate the TMJ diseases into microtrauma and macrotrauma. Both forms may show a loss of function and an audible TMJ clicking. 23 joints had a macrotrauma (disk displacement with reduction, 20 times; disk displacement without reduction, 3 times). In 8 joints, a microtrauma was found. 3 joints showed a subluxation. In 4 uncertain cases, the diagnosis was confirmed with the help of magnetic resonance imaging (MRI). All patients with a diagnosed arthrogenic disorder received adequate treatment with reposition splints. Our initial results show that 3-dimensional electronic axiography can be a good aid in further characterization of craniomandibular disorders and permits an effective therapy.

Female↗
PubMed1999

The paleocortical ventricle is the origin of reelin-expressing neurons in the marginal zone of the foetal human neocortex.

The subpial granular layer (SGL) is a transient cell layer in the cortical marginal zone during the period of neuronal migration into the cortical plate. The origin of the SGL has been studied by immunocytochemistry for calretinin (CR) and reelin in human foetuses from 11 to 40 gestational weeks (GW). At 11 GW, the paleocortical ventricle, a rostral dilatation of the lateral ventricle, gives rise to two fountainheads: a medial fountainhead provides neurons for the marginal zone (MZ) of the rostral cortex and rostral hippocampal rudiment, while multiple cell streams migrate from a lateral fountainhead into the MZ of the paleocortex and insula. The latero-medial gradient of neuronal packing density in the neocortical MZ indicates that migration extends farther into the neocortex. Neurons express CR already in the retrobulbar ventricular zone; they express reelin only as they approach the MZ of the paleocortex and rostral archicortex. At 16/17 GW, large numbers of CR-immunoreactive granule cells originate from the same fountainheads, and then direct medially, toward the surface of the anterior perforated substance, and laterally, into the paleocortical MZ, from where they continue into the neocortical SGL following a ventrolateral to dorsomedial gradient. From 13 to 18 GW, reelin is expressed by a subpopulation of granule cells and by Cajal-Retzius-like neurons. By 22 GW, the paleocortical ventricle undergoes regression and no longer supplies the SGL. Our results show that the paleocortical ventricle gives rise to a stream of neurons which extends over the cortical MZ as the subpial granular layer. The fact that SGL derivatives express reelin suggests that this transient cell layer may play a significant role in the establishment of the complex cytoarchitecture of the cerebral cortex.

Calbindin 2↗
PubMed1999

Hemodynamic effects of fluid loading in acute massive pulmonary embolism.

OBJECTIVE: To assess the hemodynamic effects of fluid loading in patients with acute circulatory failure caused by acute massive pulmonary embolism (AMPE). DESIGN: Prospective study. SETTING: Respiratory critical care unit of a university hospital. PATIENTS: Thirteen patients free of previous cardiopulmonary disease with angiographically proven AMPE (Miller index = 24 +/- 1), with acute circulatory failure defined by a cardiac index (CI) lower than 2.5 L/min/m2. INTERVENTION: Infusion of 500 mL of dextran 40 over 20 mins. MEASUREMENTS AND MAIN RESULTS: Fluid loading induced a substantial increase in right atrial pressure from 9 +/- 1 mm Hg to 17 +/- 1 mm Hg and in right ventricular end-diastolic volume index from 123 +/- 14 mL/m2 to 150 +/- 11 mL/m2 (p < .05 for both comparisons). The increase in right ventricular preload was associated with an increase in Cl from 1.6 +/- 0.1 to 2.0 +/- 0.1 L/min/m2 (p < .05), whereas right ventricular ejection fraction (15 +/- 3% at baseline vs. 16 +/- 3% after fluid loading) and total pulmonary vascular resistance index (1689 +/- 187 dyne x sec/cm5 x m2 at baseline vs. 1492 +/- 166 dyne x sec/ cm5 x m2 after fluid loading) remained unchanged. The increase in Cl induced by fluid loading was inversely correlated to baseline right ventricular end-diastolic volume index (r = -.89 ; p< .05). CONCLUSIONS: These results suggest that fluid loading can improve hemodynamic status in patients with acute circulatory failure caused by AMPE.

Acute Disease↗
PubMed1999

Identification and characterization of bovine herpesvirus type 5 glycoprotein H gene and gene products.

Bovine herpesvirus type 5 (BHV-5) is the causative agent of a fatal meningo-encephalitis in calves and is closely related to BHV-1 which causes infectious bovine rhinotracheitis. The gene encoding BHV-5 glycoprotein gH was sequenced. A high degree of conservation was found between BHV-1 and BHV-5 deduced gH amino acid sequences (86. 4%), which is also observed for all alphaherpesvirus gH sequences. Transcriptional analysis revealed a 3.1 kb mRNA as the specific gH transcript which was detected 2 h post-infection (p.i.). Twelve out of twenty-one MAbs directed against BHV-1 gH immunoprecipitated a 108-110 kDa glycoprotein, which was then designated BHV-5 gH. Synthesis and intracellular processing of BHV- 5 gH was analysed in infected MDBK cells using gH cross-reacting MAbs. Glycoprotein gH was expressed as a beta-gamma protein, detected by radioimmunoprecipitation as early as 3 h p.i. Glycosylation studies indicated that BHV-5 gH contains N-linked carbohydrates which are essential for the recognition of the protein by the MAbs. This suggests that N-linked glycans are involved in protein folding or are targets for the gH cross-reacting MAbs. Plaque- reduction neutralization assays showed that at least one BHV-1 gH antigenic domain is lacking in BHV-5 which may possibly relate to in vivo differences in virus tropism.

Alphaherpesvirinae↗
PubMed1999

Cardiorespiratory efficacy of thrombolytic therapy in acute massive pulmonary embolism: identification of predictive factors.

The aim of this study was to evaluate the contribution of clinical, angiographic and haemodynamic findings in predicting the cardiorespiratory efficacy of thrombolytic therapy in acute massive pulmonary embolism. Haemodynamic measurements and pulmonary angiography were performed before (H0) and 12 h after (H12) initiating thrombolytic therapy in 23 patients with acute massive pulmonary embolism (Miller index > or =20/34), and free of prior cardiopulmonary disease. Patients were divided into two groups according to the variation in oxygen delivery (deltaDO2) between H0 and H12: deltaDO2 >20% (responders, n=10) and deltaDO2 < or =20% (nonresponders, n=13). Before thrombolysis, clinical and angiographic findings were similar in both groups. Mean right atrial pressure (RAP) and total pulmonary (vascular) resistance (TPR) were higher, while cardiac index (CI), DO2 and mixed venous oxygen saturation (Sv,O2) were lower in responders. DO2 and Sv,O2 were more closely correlated with deltaDO2 than RAP, TPR and CI. Eight out of the 10 responders and two out of the 13 nonresponders had an Sv,O2 <55%, while nine of the responders and two of the nonresponders had a DO2 <350 mL x min(-1) x m(-2). In conclusion, the initial oxygen delivery and mixed venous oxygen saturation may predict the cardiorespiratory efficacy of thrombolytic therapy in acute massive pulmonary embolism. When pulmonary angiography is performed, measurement of mixed venous oxygen saturation may be a simple method by which to select patients for thrombolytic therapy.

Acute Disease↗