Biomedical subjects

R Meyer

Publications and source records attributed to R Meyer.

At least 163 records · Page 9Linked to original sources

PubMed1995

Modified trichrome staining technique of the nerve to determine proximal nerve viability.

Normal myelinated fibers are stained "red" by modified trichrome staining of the frozen section of the nerve. We have used this technique for rapid assessment of the anatomical integrity of the proximal nerve stump by identifying well-preserved myelinated fibers. This technique can also identify degenerating and degenerated myelinated fibers, fibrosis, and inflammatory cells. We report three cases in which the practical usefulness of this technique is demonstrated.

Cell Survival↗

PubMed1995

Spectroscopic characterization of rhinoviral protease 2A: Zn is essential for the structural integrity.

Recently, protease 2A of human rhinovirus 2 (HRV2 2A) was shown to require a zinc ion for the formation of an active enzyme although zinc is not involved mechanistically. The data presented clearly show that the zinc ion bound to a picornaviral-specific motif represents an essential component of the native structure, probably representing a new Zn-binding motif. This structure, containing mostly beta-strand elements as shown by CD spectroscopy, changes drastically upon removal of zinc. The zinc-depleted form does represent an intermediate with mostly unchanged secondary structure, but not a fully denatured random coil as obtained by guanidinium hydrochloride. This is indicated by the blue-shifted fluorescence spectra and by CD. The native protein exhibited a cooperative phase transition at 53 degrees C. In contrast, the zinc-depleted form did not show any transition at all, again demonstrating the stabilizing role of the zinc ion. A structural intermediate was observed during thermal and pH denaturation that may represent a molten globule, as suggested by its ANS binding.

Circular Dichroism↗

PubMed1995

[Detection of genetically engineered plants by polymerase chain reaction (PCR) using the FLAVR SAVR tomato as an example].

In this study, a practical approach for the detection of a genetically engineered tomato is demonstrated by polymerase chain reaction (PCR) assays. The Flavr Savr tomato available on the market which was used as an example, contains a resistance gene for the antibiotic kanamycin (kanr) and a gene construct for the inhibition of fruit ripening and softening (antisense polygalacturonase). The presence of these DNA's could only be detected in the genetically engineered tomato.

Base Sequence↗

PubMed1995

Effects of guanyl nucleotides on CCKB receptor binding in brain tissue and continuous cell lines: a comparative study.

The effects of non-hydrolyzable guanyl nucleotide analogue GTP-gamma S on CCKB receptor binding in human and guinea-pig cortex, Jurkat T-cells, rat pituitary GH3 cells, rat glioma C6 cells and human small cell lung cancer NCI-H69 cells were investigated by using [3H]CCK-8S saturation and competition binding studies. GTP-gamma S caused inhibition of specific [3H]CCK-8S binding in a concentration dependent manner with a plateau at 10-25 microM. 25 microM GTP-gamma S resulted in a small but significant increase in Kd and IC50 values with amount very similar in all CCKB receptor models tested. However, the maximal number of specific [3H]CCK-8S binding sites (Bmax) was unaffected. Results suggest that CCKB receptors are G-protein coupled in a similar way to human and guinea-pig cortex, Jurkat cells, GH3 cells, C6 cells and NCI-H69 cells.

Animals↗

PubMed1995

Polymerase chain reaction (PCR) for detection of pathogenic microorganisms in bacteriological monitoring of dairy products.

The presence of pathogenic bacteria poses a serious problem in sustaining the safety of dairy products. Microbiological routine controls of these products make use of selective culture techniques. To detect pathogenic species, isolated colonies are characterized by specific metabolic activities and by serotyping. We present an alternative biochemical approach that does not require culture of bacteria. The total bacterial populations of food samples were isolated by centrifugation and analysed by PCRs specific for pathogenic species. A total of 90 raw milk samples and dairy products made from raw milk were screened by this method for the presence of Listeria monocytogenes, Escherichia coli, enterotoxigenic E. coli, Campylobacter jejuni and C. coli. Detection rates were 12/90 (13%) for L. monocytogenes, 41/90 (46%) for E. coli, 18/90 (20%) for enterotoxigenic E. coli producing heat-labile toxin type I or heat-stable toxin type I, and 6/90 (7%) for C. jejuni or C. coli. Except for the use of different amplification primers, this approach is identical for any bacterial species to be detected. Direct PCR analysis of food samples offers rapid screening for the presence of specific bacteria and enables selection of critical samples prior to culture.

Animals↗

PubMed1995

The use of anti-D to improve post-transfusion platelet response: a randomized trial.

Patients undergoing induction chemotherapy for acute leukaemia often become refractory to platelet transfusions. Increased clearance of transfused platelets due to alloimmune destruction has been identified as one of the primary mechanisms contributing to this refractory state. We performed a double-blind randomized trial to determine whether the administration of anti-D to Rh-positive individuals could prevent the refractory state and improve post-transfusion platelet response. Rh-positive patients with acute leukaemia undergoing induction chemotherapy and requiring platelet transfusions were allocated to weekly intravenous anti-D (20 micrograms/kg) or placebo. Platelets and red cell concentrates were administered according to standardized transfusion guidelines. Outcome measures included platelet transfusion utilization, red cell utilization, platelet recovery 18-24 h post-infusion, and the percentage of patients refractory to platelet transfusion. There were 43 patients studied: 21 received anti-D and 22 saline placebo. The mean number of platelet concentrates required per day of observation was 0.59 (SD 0.22) in the anti-D group and 0.61 (SD 0.22) in the placebo group, P = 0.86. No difference was detected between groups in terms of platelet recovery post-infusion, refractoriness to platelet transfusion or frequency of infection (P = 0.97). Red cell concentrate utilization was significantly increased in the anti-D group compared to the placebo group, 0.58 units per day versus 0.37 units per day respectively, P = 0.005. We conclude that the use of anti-D did not improve post-transfusion platelet response in Rh positive patients with acute leukaemia, but did result in an increased need for red cell transfusion.

Acute Disease↗

PubMed1995

The incidence of sleeping problems in preterm and fullterm infants discharged from neonatal special care units: an epidemiological longitudinal study.

Anecdotal reports have suggested that sleeping problems are a frequent complaint from parents of preterm infants. This prospective epidemiological study examined the incidence and stability of sleeping problems of very preterm (< 32 weeks gestation at birth), preterm (32-36 weeks gestation) and fullterm infants, all admitted to special care baby units (SCBU) after birth, in comparison to healthy term infants over the first 5 years of life. Preterm infants were found to have fewer and shorter night-wakings at 5 months. No differences in sleeping behaviour compared with healthy term children were found at 20 and 56 months of age. Similar significant, and moderate, stability of nightwaking from one age to the next were found for exSCBU-graduates and healthy fullterm infants. Parental interventions such as staying with the child until sleep and taking the infant into bed af night were related to nightwaking problems and increased parental distress. It is concluded that prematurity, and thus neurological immaturity and special care experience are less important than caretaking behaviour in the development of sleeping problems in both preterm and fullterm infants.

Birth Weight↗

PubMed1995

Magnetic resonance imaging of a glioblastoma of the optic chiasm. Case report.

Malignant optic glioma causing blindness was difficult to diagnose prior to the introduction of computerized tomography (CT) and magnetic resonance (MR) imaging, because earlier neuroradiological procedures often gave negative results and the clinical symptoms for this entity are not specific. In such cases only a craniotomy or postmortem examination revealed the tumor. The authors found no precise description in the literature of a malignant optic glioma diagnosed with modern imaging methods. They present a patient in whom biopsy results confirmed the CT and MR findings of glioblastoma multiforme of the optic chiasm.

Aged↗

PubMed1995

Removal of a giant cardiac fibroma from a 4-year-old child.

In an 8-month-old infant presenting with a systolic heart murmur, a cardiac tumor was diagnosed by means of 2-dimensional echocardiography, cardiac catheterization, and magnetic resonance imaging. In the following years, the child developed ventricular arrhythmias, which were controlled with antiarrhythmic drugs. The operation was undertaken when the boy was 4 years and 3 months of age. A tumor of the interventricular septum measuring 45 x 13 x 25 mm was resected in toto. The defect in the ventricular septum was closed with a Dacron patch. The postoperative course was uneventful. Histologic examination classified the tumor as a fibroma.

Blood Vessel Prosthesis↗

PubMed1994

Hydrocephalus: the zero ICP ventricle shunt (ZIPS) to control gravity shunt flow. A clinical study in 56 patients.

Significant morbidity from ventricle shunt overdrainage at 6-7 years after initial shunt placement for hydrocephalus is increasingly recognized as due to excessive gravity-flow of shunted CSF when upright. Shunts are designed primarily to control high ICP. Shunts should also mimic normal upright ICP. Normal upright ICP is -65 mm of water (vertex reference), indicating that a level of zero ICP exists at 65 mm below the brain vertex, with negative ICP above and positive ICP below that level. This normal zero ICP level must be maintained by CSF shunts to mimic normal upright ICP. This will prevent and correct CSF shunt overdrainage. The zero ICP shunt (ZIPS) by design controls this zero level with a zero pressure device (ZPD; siphon control device) installed at the normal vertical level of zero ICP (cm/mm) below the vertex (65 mm). The shunt thus prevents excessive gravity-induced CSF shunt flow. Successful use of ZIPS in 56 patients is reported (low ICP group: n = 42; high ICP group: n = 14). Follow-up is up to 4.5 years. Results show that: (1) adjustability of ZPD level can achieve the desired clinical results; (2) the level of ZPD installed correlates within 4 mm of upright ICP attained; (3) the optimal level of ZPD installation to produce normal upright ICP is 65 mm below the vertex; (4) CT ventricle size, both slit ventricles and large ventricles, may or may not normalize when normal upright ICP is attained in this group of complex, previously shunted patients.

Cerebral Ventricles↗

PubMed1994

Nasal septal perforations must and can be closed.

In this time of increasing occurrence of septal perforations caused by cocaine abuse, the plastic surgeon who deals mainly in rhinoplasty must learn to treat these defects with sophisticated methods. Too many septal perforations, especially large ones, are not treated because the surgical techniques are difficult. This article describes and illustrates two methods that close all kinds of perforations. Local flaps should be considered obsolete. A perforation up to 4 cm in diameter must be repaired in one step. This includes wide dissection of the mucoperichondrium and mucoperiosteum, suture of the hole on both sides, and interposition of parietal fascia or cartilage, sometimes with the help of bilateral small buccal flaps to cover the gap between the columella and the dissected mucoperichondrium containing the closed perforation on both sides. For closure of perforations greater than 4 cm in diameter, a three-step procedure which uses a composite three-layered buccal flap including ear concha cartilage is described. In the second step, the spoon-shaped flap is fed into the nasal cavity to fill the septal defect. The third step divides the pedicle. In many cases a unilateral or bilateral alotomy or the section of the columellar base may facilitate the suture of the flaps.

Humans↗

PubMed1994

The "Freddy frog" lateral view of the chest in children. A preliminary report.

A special new lateral view of the chest, called the "Freddy Frog" view, was used in 50 children between the ages of 5 and 7 years. This resulted in optimal demonstration of the superior mediastinal and superior bony structures without superficial overlying soft tissues and can replace the separate lateral views of the neck and chest in cases of stridor.

Age Factors↗

PubMed1994

Noninvasive diagnosis of cardiac rejection through echocardiographic tissue characterization.

Ultrasonic tissue characterization is based on the assumption that microscopic tissue structures are identifiable by their acoustic properties. Our study group consisted of 23 cardiac recipients. Two-dimensional images were obtained within 2 hours of endomyocardial biopsy. The end-diastolic echo frames were digitized into the matrix of an image-processing system. A region of interest was placed into the anteroseptal segment of the left ventricle. The texture within the region of interest was analyzed using four major groups of texture analysis (first-order histogram, co-occurrence matrix, run-length statistic, and power spectrum). A total of 408 echocardiographic examinations were compared with histologic findings. The 117 initially calculated texture parameters were reduced incrementally using a series of discriminant analyses. A set of three texture parameters (inverse difference moment undirected, run-length nonuniformity vertical, and sector sum) was able to describe changed echocardiographic texture when rejection occurred. Using these three parameters, echocardiographic sensitivity was 89.0% and specificity was 83.6% for moderate rejection. We conclude that cardiac rejection is associated with echocardiographic texture alterations and that serial echocardiographic texture analysis can reliably identify rejection.

Adult↗

PubMed1994

An alternative interpretation of the heat capacity changes associated with protein unfolding.

The present study devises a method to get quantitative information for proteins on the theoretically important heat capacity at constant volume. For this purpose expansion coefficients of both the native and unfolded state of a variety of proteins have been determined and used together with compressibility coefficients to calculate the difference between isobaric and isochoric heat capacity, (cp - cv), for the unfolding transition. This difference delta (cp - cv) = (c - c) - (c - c) turns out to be a positive number that is larger than the experimental isobaric heat capacity change (formula:see text) [corrected] for the proteins studied. The generally observed positive heat capacity change on unfolding can therefore alternatively be interpreted as resulting from the difference in work involved in changing the intra- and intermolecular interactions including the weak, highly distance-dependent, van der Waals interactions, for the unfolded and native state, respectively. The difference in expansion work against the atmospheric pressure is negligible. This macroscopic interpretation cannot rule out that part of the denaturational heat capacity increase is also due to the different interaction with water of the native and unfolded conformations of the protein.

Calorimetry↗

PubMed1994

[The necessity of conducting to the end the activities of vector control in the onchocerciasis control program in west Africa: recall of the stakes and proposal of a minimum budget for the period 1998-2002].

After a brief presentation of the Onchocerciasis Control Programme in West Africa (OCP), the authors realize the health and socioeconomic consequences that could follow a cessation of larvicide treatment before 2002 in the south-eastern and western extensions of the Programme. Taking into account that OCP activities are theoretically supported until 1997, but aware of financial constraints that will probably increase from now to 2002, this paper proposes an a minima estimation of the residual vector control activities for a "phasing out" spread out for five years (1998-2002). These estimations essentially concern the larvicide coverage, the insecticides used, the entomological surveillance, the logistical support and their financial aspects. As far as 48 U.S. $ million amount for 5 years are concerned, the budget allocated for vector control activities should not exceed the third of the global amount allocated to OCP for the actual fourth financial phase of the Programme (1992-1997).

Africa, Western↗

PubMed1994

Challenge with high concentrations of cyclic AMP induces transient changes in the cytosolic free calcium concentration in Dictyostelium discoideum.

Dictyostelium discoideum cells use cyclic AMP (cAMP) for chemotactic signaling as well as for differentiation. The precise regulation of the cytosolic Ca2+ concentration ([Ca2+]i) seems to play a key role for both processes. We performed single cell measurements of [Ca2+]i in amoebae that were starved in suspension for various times and scrape-loaded with the Ca2+ indicator fura-2. Stimulation of cells with cAMP at the concentration required to induce gene expression (> or = 100 microM) elicited a global transient increase in [Ca2+]i that depended on the presence of external Ca2+. Both vegetative and aggregation-competent cells displayed a rise in [Ca2+]i, with aggregation-competent cells responding more often than vegetative cells. Basal [Ca2+]i in the presence of Ca2+ was high in vegetative cells and declined during development; the cAMP-induced rise in [Ca2+]i was higher and lasted longer in vegetative cells than in aggregative cells. The addition of 2'-deoxy-cAMP, which binds to the cAMP receptor, induced an increase in [Ca2+]i, whereas the membrane-permeant analogue 8-bromo-cAMP that has a low affinity for the receptor but activates cAMP-dependent protein kinase had no effect. This indicates that the change in [Ca2+]i is mediated by the cell surface cAMP receptor. Since HC85 mutant cells, which lack the G alpha 2 subunit of the G-protein that couples the receptor to phospholipase C, also responded to stimulation with cAMP, the Ca2+ influx does not seem to be triggered by the phosphoinositide signaling cascade.(ABSTRACT TRUNCATED AT 250 WORDS)

8-Bromo Cyclic Adenosine Monophosphate↗

PubMed1994

[Incidence and persistence of problems at sleep onset and sleep continuation in the preschool period: results of a prospective study of a representative sample in Bavaria].

The prevalence and persistence of sleeping problems was studied in a prospective investigation of a representative sample of 432 German children at the ages of 5, 20 and 56 months. 21.5% of children had night waking problems at 5 months, 21.8% at 20 months and 13.3% at 56 months. Falling asleep difficulties were diagnosed in 12.1% of 4-5 year olds. One in four of five year-olds slept regularly in the bed with the parents (co-sleeping). Children with night waking problems had a 2.2 to 2.5 fold increased risk to remain nightwakers from one assessment point to the next compared with non-wakers. 7 to 14% of parents were distressed by their children's sleeping behaviour. Parental behaviour often contributed to continued sleeping problems because the children were not supported in acquiring appropriate skills to settle to sleep unaided. A developmental model for the treatment of sleeping problems is discussed.

Child, Preschool↗

PubMed1994

Hyperinsulinism in patients with coronary artery disease.

AIM: To assess the clinical impact of hyperinsulinism and major coronary risk factors in patients with angiographically documented or excluded coronary artery disease (CAD), a clinical study was carried out in 268 men admitted for left heart catheterization. METHODS: Fasting immunoreactive insulin (IRI) levels were correlated to all major cardiovascular risk factors and to the presence and degree of CAD. RESULTS: IRI levels were correlated significantly with the degree of CAD (one-vessel disease: mean IRI 9.45 microU/ml +/- 0.43 SEM; two-vessel disease: mean IRI 10.4 microU/ml +/- 0.71 SEM; three-vessel disease: mean IRI 11.88 microU/ml +/- 0.98 SEM) and inversely to the high-density lipoprotein level (P < 0.05). In patients with arterial hypertension, IRI levels were elevated, without a significant difference between those with and those without CAD, whereas the IRI levels of non-hypertensive men with CAD (n = 81; mean IRI 9.85 microU/ml +/- 0.51 SEM) differed significantly (P < 0.05) from those of non-hypertensive men without CAD (n = 59; mean IRI 7.76 microU/ml +/- 0.43 SEM). IRI levels were significantly higher (P < 0.05) in obese patients (n = 65; mean IRI 11.68 microU/ml +/- 0.70 SEM versus n = 203; mean IRI 9.32 microU/ml +/- 0.34 SEM), in patients with elevated triglycerides (n = 58 mean IRI 11.59 microU/ml +/- 0.81 SEM versus n = 210; mean IRI 9.42 microU/ml +/- 0.33 SEM), and in patients with lowered HDL cholesterol (n = 178; mean IRI 11.06 microU/ml +/- 0.63 SEM versus n = 90; mean IRI 9.29 microU/ml +/- 0.34 SEM). Diabetic patients on angiotensin converting enzyme inhibitor therapy (n = 11; mean IRI 7.91 microU/ml +/- 0.91 SEM) had significantly (P < 0.05) lower IRI levels than those not treated with ACE inhibitors (n = 25; mean IRI 12.96 microU/ml +/- 1.47 SEM). IRI levels exceeding 8 microU/ml were associated with a 1.98-fold risk for CAD compared with IRI levels below 8 microU/ml. Stepwise logistic regression showed that insulin was an independent determinant of CAD. CONCLUSION: Knowledge of the fasting insulin level is an important contribution to the identification of patients with, or at risk of, CAD.

Angiotensin-Converting Enzyme Inhibitors↗