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Biomedical subjects

B Meyer

Publications and source records attributed to B Meyer.

At least 217 records · Page 12Linked to original sources
PubMed1992

[Clinical aspects of arrhythmias].

Arrhythmias are frequent and occur in normal individuals as well as in patients with structural heart disease. In supraventricular arrhythmias the indication for treatment is mainly based on symptoms. In atrial fibrillation the thromboembolic risk has to be taken into account. In ventricular arrhythmias, especially in combination with significant structural heart disease, prognostic considerations play an important role in decision-making.

Arrhythmias, Cardiac↗
PubMed1992

[Drug therapy in supraventricular arrhythmia].

In view of their potentially dangerous proarrhythmic effects, antiarrhythmic drugs should only be prescribed for patients with poorly tolerated symptomatic supraventricular arrhythmias. The choice of a suitable preparation depends not only on the type of arrhythmia, but also on the underlying heart disease and left-ventricular function. Digoxin, verapamil, sotalol and quinidine remain first-line drugs, while in view of recent trials the type-1c antiarrhythmics (flecainide) should only be given in cases resistant to other agents. Amiodarone is also an important and efficacious "reserve" antiarrhythmic, which has to be utilized at low doses to avoid its well-known side effects.

Amiodarone↗
PubMed1992

The solution conformation of sialyl-alpha (2----6)-lactose studied by modern NMR techniques and Monte Carlo simulations.

We present a comprehensive strategy for detailed characterization of the solution conformations of oligosaccharides by NMR spectroscopy and force-field calculations. Our experimental strategy generates a number of interglycosidic spatial constraints that is sufficiently large to allow us to determine glycosidic linkage conformations with a precision heretofore unachievable. In addition to the commonly used [1H,1H] NOE contacts between aliphatic protons, our constraints are: (a) homonuclear NOEs of hydroxyl protons in H2O to other protons in the oligosaccharide, (b) heteronuclear [1H,13C] NOEs, (c) isotope effects of O1H/O2H hydroxyl groups on 13C chemical shifts, and (d) long-range heteronuclear scalar couplings across glycosidic bonds. We have used this approach to study the trisaccharide sialyl-alpha (2----6)-lactose in aqueous solution. The experimentally determined geometrical constraints were compared to results obtained from force-field calculations based on Metropolis Monte Carlo simulations. The molecule was found to exist in 2 families of conformers. The preferred conformations of the alpha (2----6)-linkage of the trisaccharide are best described by an equilibrium of 2 conformers with phi angles at -60 degrees or 180 degrees and of the 3 staggered rotamers of the omega angle with a predominant gt conformer. Three intramolecular hydrogen bonds, involving the hydroxyl protons on C8 and C7 of the sialic acid residue and on C3 of the reducing-end glucose residue, contribute significantly to the conformational stability of the trisaccharide in aqueous solution.

Carbohydrate Conformation↗
PubMed1992

Do motor evoked potentials allow quantitative assessment of motor function in patients with spinal cord lesions?

Motor evoked potentials (MEP) were recorded in a total of 110 patients with tumorous (n = 39) and non-tumorous (n = 71) lesions of the cervical (n = 59), thoracic (n = 37) and thoracolumbar (n = 14) spinal cord. In all cases MEP were elicited by electrical stimulations, and in 50 of them also by magnetoelectric stimulation, of the motor cortex. The peripheral conduction time was determined by electrical stimulation of the lumbar nerve roots. It was the aim of this study to determine whether 1. MEP are sensitive for detection of lesions along the spinal cord and 2. whether they allow quantitative assessment of motor function. To achieve this goal, we compared potential and clinical findings of our patients, each divided into seven categories. Our results clearly showed the high sensitivity of MEP for semi-quantitative evaluation of motor function, as there were no false negative results in our series. Moreover, unilaterally accentuated motor deficits correlated significantly with changes in MEP, which were affected more strongly on the corresponding side (Student's t-test, alpha = 0.05). However, clinical and electrophysiological findings did not correlate in the quantitative evaluation of the motor status as established by variance analysis (F = 0.52). There was no difference in results with respect to the electrical and magnetoelectric stimulation technique. Our results lead to the following conclusions. MEP are sensitive for semi-quantitative evaluation of spinal motor function; however, MEP do not allow quantification of the clinical motor status.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Clinical results of a 15-filter digital auditory prosthesis using selective amplification and compression.

Classical hearing aid efficiency was compared with that of a 15-filter digital auditory prosthesis in 23 patients suffering from partial sensorineural hearing loss. This device contains a microprocessor 320C25 from TEXAS Instruments. The sound signal is analysed at a sampling rate of 16 kHz. With the use of a Fast Fourier Transform (FFT), it provides the system with 15 energy levels at frequencies ranging from 0 to 8 kHz. The energy of each frequency band is multiplied by a coefficient stored in the device memory and directly dependent on the patient's audiometric specificities. The 15 signals are then synthesized by inverse FFT and mixed in a loudspeaker. The prosthesis is a rechargable battery powered 4 x 10 x 15 cm box programmable through a PC. The clinical results obtained with this 15-filter digital prosthesis are discussed and compared with the performances of present classical hearing aids.

Auditory Threshold↗
PubMed1992

Centrofacial malignant granulomas. Clinicopathologic study of 40 cases and review of the literature.

An important problem in the treatment of centrofacial ulcerations is to establish a precise diagnosis, since similar clinical and microscopic findings can result from many different causes (as in the centrofacial malignant granuloma syndrome [CFMG]). A comprehensive surgical biopsy protocol (known as SNFMI/GMCF), involving microbiology, parasitology, immunology and pathology laboratories, allowed us to evaluate and to treat 40 cases of CFMG, who form the basis of this report. In 13 of them, specific diagnoses were found and curative treatments could be given. In the remaining 27, the optical microscopy pattern met the criteria for CFMG without identifiable origin or the presence of so-called lethal midline granulomas; however, a more precise evaluation with the help of immunofluorescence studies led to the recognition of malignant lymphoma (ulcerative lymphoma of the midface [ULM]). Most of these lymphomas belonged to the T cell lineage; the others were of B lymphoid origin, or, more rarely, of histiocytic origin. Patients with ULM received radiotherapy and chemotherapy with a response rate of 70.3%; however, the toxicity was significant, with frequent occurrence of chemotherapy-induced neutropenia followed by severe infectious facial cellulitis. Six patients were enrolled in a preliminary open trial of treatment with recombinant alpha-2b interferon with little success. Three patients were treated with radiation therapy only, and survived. Thus, CFMG is a syndrome with specific causes and treatments, requiring multiple extensive biopsies to make the correct diagnosis. The recognition of ULM as the cause of the previously called "lethal midline granulomas" leads logically to the use of chemotherapy with growth factors in order to ameliorate its bad prognosis.

Adolescent↗
PubMed1992

Aortic and mitral valve disease in patients with end stage renal failure on long-term haemodialysis.

OBJECTIVE: To identify valvar heart disease in patients with chronic uraemia by conventional and colour coded Doppler echocardiography. DESIGN: Case series of an unselected group of 62 patients with end stage renal failure. SETTING: Centre for haemodialysis in a referral hospital in Switzerland. PATIENTS: 62 patients on chronic haemodialysis. MAIN OUTCOME MEASURES: Frequency of structural and functional valve abnormalities and their relation to clinical findings. RESULTS: Structural changes were seen in 40 (64%) of 62 patients after 50 months (range 3-178 months) on haemodialysis. The mitral annulus and aortic cusps were thickened in 25 (40%) and in 34 (55%) patients respectively. Aortic stenosis was present in eight (mean (SD) age 60.5 (8.5) years), with a maximal instantaneous pressure gradient of 41 (14) mm Hg. Aortic regurgitation was seen in eight, mitral regurgitation in seven, and mitral stenosis in three patients. Patients with aortic stenosis had been on haemodialysis for significantly longer than the remaining patients (101 (43) v 46 (43) months, p = 0.01) and had significantly higher concentrations of serum alkaline phosphatase (176 (89) v 117 (47) IU/l, p less than 0.01) and of parathyroid hormone (54 (66) v 19 (29) ng/ml, p less than 0.02). CONCLUSIONS: Patients on long-term haemodialysis had an increased frequency of haemodynamically relevant changes in the aortic and mitral valves. The degenerative valve disease may be related in part to the duration of haemodialysis and to alterations in calcium metabolism as indicated by increased plasma concentrations of alkaline phosphatase and parathyroid hormone.

Alkaline Phosphatase↗
PubMed1992

Influence of long-term amelioration of anemia and blood pressure control on left ventricular hypertrophy in hemodialyzed patients.

The course of left ventricular hypertrophy was investigated in anemic hemodialysis patients treated with recombinant human erythropoietin (r-huEPO). 12 patients, aged 60.8 +/- 9.9 years (mean +/- SD) were treated for 18.8 +/- 2.7 months. Left ventricular size was estimated by echocardiography performed before treatment and at least 12 months after relieving anemia. Patients had signs of left ventricular and/or asymmetric septal hypertrophy when compared with a nonanemic and normotensive control group matched for sex and age. At baseline, hemoglobin (Hb) was 8.6 +/- 0.7 g/dl; interventricular septum thickness (IVST) was 1.75 +/- 0.34 cm, left ventricular posterior wall thickness (LVPWT) 1.32 +/- 0.19 cm, left ventricular muscle mass index (LVMI) 222.7 +/- 41 g/m2 and blood pressure (BP) 146.4 +/- 10/81.6 +/- 6 mm Hg. Hb rose to 11.4 +/- 1.2 g/dl (p less than 0.001); IVST and LVMI decreased to 1.42 +/- 0.35 cm (p less than 0.02) and 155.4 +/- 25.1 g/m2 (p less than 0.001); LVPWT and BP remained unchanged (1.30 +/- 0.26 cm and 146.8 +/- 16.9/81.2 +/- 7.8 mm Hg) at the end of the study. During the observation period, two groups of 5 and 7 patients differed from each other. The group of 5 patients had higher BP values (158.9 +/- 9.8/86.5 +/- 5.3 vs. 140.0 +/- 9.5/79.2 +/- 6.8 mm Hg, p less than 0.01), and the period with Hb values above 10 g/dl was shorter (14.5 +/- 2.4 vs. 17.8 +/- 2.4 months, p less than 0.05). These 5 patients failed to show a significant decrease in IVST and LVMI.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Peanut agglutinin (lectin from Arachis hypogaea) binding to hemopoietic cells: an immunophenotypic study using a biotin streptavidin technique.

The lectin peanut agglutinin (PNA) was used to study the surface carbohydrate expression of galactose beta 1, 3, N-acetylgalactosamine by normal and malignant hemopoietic cells. Immunostaining was performed using biotinylated PNA and a streptavidin-alkaline phosphatase staining technique on 78 patients. The study was undertaken to enlarge on previous reports of lectin binding to cells of hemopoietic origin and to establish the potential role of biotinylated PNA as a component of an immunotoxin for in vitro purging of bone marrow in patients with multiple myeloma. In normals only monocytes, macrophages, centroblasts and plasma cells showed reactivity. Of the hematological malignancies, all cases of multiple myeloma were positive and non-Hodgkin's lymphoma cases with a large cell component had positive centroblasts. Two of 5 cases of acute myelomonocytic leukemia, one case of chronic myelomonocytic leukemia and one case of pleomorphic T cell non-Hodgkin's lymphoma showed PNA positive neoplastic cells. The reactivity of biotinylated PNA with centroblasts and plasma cells suggests that it may be of potential value when linked to a streptavidin-ricin conjugate in the in vitro purging of bone marrow of patients with multiple myeloma prior to autologous bone marrow transplantation.

Bacterial Proteins↗
PubMed1992

[Long-term follow-up and therapeutic results of the protocol of the National Society of Internal Medicine in centrofacial malignant granuloma. Report of 40 cases].

We have studied 40 cases of mediofacial necrosis with no specific diagnosis on biopsy. After an exhaustive work-up we reached a specific diagnosis in 13 patients (Wegener's granulomatosis in 7, classical malignant lymphoma of the nose in 3, squamous cell carcinoma = "goundou" in 1, syphilis and tuberculosis in 1, aspergillosis in 1). Those patients received the appropriate treatments with good results. The remaining 27 patients, however, had ulcerative lymphomas of the midface (according to the immunofluorescence and molecular biology techniques). Their fate was worse since only 15% remain alive on the long-term, despite intensive treatments with chemotherapy, radiotherapy, interferon, artificial nutrition and antibiotics as needed. We present a new protocol with intensified chemotherapy and growth factor treatment in order to ameliorate the very poor prognosis of these patients.

Adolescent↗
PubMed1992

[Functional results of subtotal and partial colectomy in therapy-resistant chronic constipation. A follow-up study of 32 patients].

In 32 female patients with severe constipation subtotal (n = 27) or partial (n = 5) colectomy was performed. In 8 cases slow transit constipation was preexistent, 24 patients had a megacolon/dolichocolon. Ileosigmoid anastomosis was found to show the most favourable results. None of these patients complained of constipation postoperatively and all of them reported regular (daily) bowel movements. Incontinence for flatus and/or liquid stools was less likely to occur with ileosigmoid than with rectal anastomosis (29 versus 46%).

Adult↗
PubMed1992

[Improvement of clinical results by digitalization of a single channel cochlear implant].

For 1973 we have been among the first to claim the multichannel cochlear implant superiority regarding single channel efficacy. However we actually thing that single channel cochlear implant is indispensable in case of total ossified cochlea, and very useful when efficacy/coast ratio must be considered. In order to narrow the gap between multi and single channel device efficacy, we used the new microprocessors possibilities to digitalize the analogic emietter of the single channel system, which we designed in 1987. Owing to a PC keyboard the new emietter allows the speech therapist to select the frequency band width of the input signal, and to determine the threshold level and the dynamic value as a function of six steps values of the stimulus wave frequency. These improvements supply the patient with a better speech intelligibility excepted for vowels discrimination. Comparison of clinical results obtained through the two analogic and digital systems are reported on 4 post lingually and 4 pre lingually deaf patients.

Adolescent↗
PubMed1992

[Indications and results of cochlear implants in young children].

In order to determine the criteria for patient selection and the preoperative prognostic factors for hearing recovery after cochlear implants in young totally dead children, the results of hearing rehabilitation were studied in 15 children who had undergone cochlear implantation at from 2 to 9 years of age. The choice of implant is determined by the permeability of the cochlear duct. A multi-system should be used, except when the cochlea is totally ossified. The reliability and efficacy of mono and multi system implants make it possible to offer a solution to the urgent therapeutic problems posed by total deafness in the young child.

Age Factors↗
PubMed1992

Integrating the UMLS into VNS Retriever.

We are developing a networked resource for the National Library of Medicine's Unified Medical Language System. We call this resource the UMLS Retriever, which is an instance of our VNS Retriever architecture. Our prototype user interface makes use of the Virtual Notebook System Browser. The development of a networked UMLS service will result in numerous advantages to our user community.

Computer Communication Networks↗
PubMed1992

[3D imaging of the labyrinth: application to candidates for cochlear implant].

Cochlear implantation is a treatment for profound bilateral cochlear hearing loss. Two broad varieties of cochlear implants are used: single or multichannel device (22- channel) inserted either into the cochlea (tympanic ramp) or on the promontory on round window Imaging modalities have to predict cochlear patency prior surgery, an essential factor for choosing between intra or extra cochlear implant. Since March 1991, we have investigated 23 implant candidates to evaluate cochlear patency prior surgery, 6 patients underwent surgery: 4 had a multichannel and 2 had a monochannel electrode. Both CT and MRI play a role in pre operative study. CT easily predicts cochlear ossification and labyrinthine malformations MRI (3 D applications) with T 2 Weighted images, one millimeter thick, more clearly depicts labyrinthine liquid and can predict cochlear fibrosis before ossification.

Cochlear Implants↗
PubMed1991

Syntheses of disaccharides with (1----4)-beta glycosidic linkages related to the 4- and 6-sulfates and the 4,6-disulfates of chondroitin.

The solution salts of the 6'-sulfate 12, the 4'-sulfate 15 and the 4',6'-disulfate 17 of benzyl 4-O-(beta-D-galactopyranosyl)-beta-D-glucopyranosiduronate 10 have been synthesized. Methyl [benzyl 2,3-di-O-benzoyl-4-O-(2,3-di-O-benzoyl-beta-D-galactopyranosyl)-beta-D-+ ++glucopyranosid]uronate (9) has been prepared as a key intermediate from benzyl 4',6'-O-benzylidene-beta-D-lactopyranoside (2). Protection of 2 at C-6 with the tert-butyldimethylsilyl group, followed by O-perbenzoylation and disilylation, gave benzyl 2,3-di-O-benzoyl-4-O-(2,3-di-O-benzoyl-4,6-O-benzylidene-beta-D-galac top yranosyl)-beta-D-glucopyranoside (7). Oxidation of the 6-position of 7 proved to be difficult. However, 7 could be converted into the tert-butyl glucuronate 8 using chromium trioxide-pyridine and tert-butanol. Simultaneous hydrolysis of the benzylidene acetal and the tert-butyl ester groups, followed by esterification of the resulting free acid with diazomethane, yielded 9. Compound was directly sulfated with sulfur trioxide-trimethylamine within 12 h to give the 6'-sulfate 11. The 4',6-disulfate 16 was accessible by running the reaction under the same conditions for 14 days. The 4'-sulfate 14 was obtained after protecting the 6'-OH group of 9 with benzoyl cyanide to give the 6'-benzoate 13 followed by sulfation under more vigorous reaction conditions. Deesterification of 9, 11, 14, and 16 was achieved by treatment with aqueous sodium hydroxide in tetrahydrofuran to give 10, 12, 15, and 17, respectively.

Carbohydrate Conformation↗