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Biomedical subjects

E Werner

Publications and source records attributed to E Werner.

At least 91 records · Page 5Linked to original sources
PubMed1994

[The effect of nimodipine on cochlear blood flow in the guinea pig].

The influence of nimodipine (Nimotop, CAS 66085-59-4), a selectively cerebrovascularly acting 1,4-dihydropyridine calcium antagonist, on the cochlear blood flow (CBF) was studied in 19 guinea pigs (6 controls). The hydrogen clearance measurements were carried out under alpha-chloralose-ethylurethane anaesthesia, artificial respiration with simultaneous control of electrocardiogram, blood pressure, body temperature and arterial pH (hourly). The indirect measurement of CBF was carried out by means of hydrogen clearance in the perilymphatic space (basal turn) before and after intravenous application of 1 microgram nimodipine/kg/min. The mean arterial blood pressure remained within the +/- 5% range of the initial value during the experiment. Under treatment with nimodipine the CBF showed a non-significant average increase of 4.69% and under placebo (20% ethanol, 17% polyethylenglycol 400, citrate buffer), a non-significant average decrease of 6.16%. The influence of nimodipine on CBF was underlined by the overcompensation of the placebo effect.

Animals↗
PubMed1993

The fidelity and dynamic response of fluid-filled catheter systems for direct measurement of lumbar cerebrospinal fluid pressure.

OBJECTIVE: The purpose of this study was to determine the fidelity of pressure signals transmitted through long, narrow (epidural) catheters inserted into the lumbar intrathecal space. METHODS: Using a model of the spinal canal we tested three epidural catheters: 20-gauge Arrow, 20-gauge Abbott, 21-gauge Portex. We (1) determined the damping coefficient and natural frequency of the three catheters, (2) correlated the static pressures measured using the three catheters compared to the true pressure in the intrathecal space, and (3) compared the response time of the three catheters connected to transducers vs U-tube manometers. RESULTS: The three catheters had high damping coefficients (alpha) (Arrow, 0.75; Abbott, 0.85; Portex, 1.10) and low natural frequencies (Arrow, 15.23 Hz; Abbott, 12.83 Hz; Portex, 9.09 Hz). The dynamic response characteristics of the catheter with the largest internal diameter (20-gauge Arrow) were adequate to reproduce pulsatile cerebrospinal fluid pressure reliably. Smaller catheters tracked the mean pressure, although oscillations were damped. Static pressure measurements from all three catheters showed good correlation with test pressures (r = 0.99; p < 0.001). Using the U-tube manometer, it required 170, 140, and 130 minutes for the Portex, Abbott, and Arrow catheters, respectively, to equilibrate with a test pressure of 30 cm H2O. The rate of rise in the U-tube manometer pressure was limited by the rate of fluid flow through the catheters. CONCLUSIONS: We found that a catheter of at least 20 gauge connected to a transducer could record pressures in the cerebrospinal fluid compartment with a high degree of fidelity. The prolonged time to reach equilibrium made U-tube manometry unsuitable for clinical use.

Catheterization↗
PubMed1993

Effects of cerebrospinal fluid drainage in patients undergoing thoracic and thoracoabdominal aortic surgery.

Cerebrospinal fluid (CSF) drainage has been reported to protect the spinal cord during surgical procedures requiring thoracic aortic cross-clamping. In 1986, CSF pressure monitoring and drainage was begun in an attempt to reduce the incidence of paraplegia associated with surgical repair of descending thoracic and thoracoabdominal aortic aneurysms (TAAA). These Group II patients (n = 50) were retrospectively compared to Group I patients (n = 49) who had undergone similar surgical procedures in the previous 3 years before CSF monitoring was introduced into this practice. Group II patients had intrathecal catheters placed for monitoring of CSF pressure and drainage of CSF to maintain the pressure < or = 15 mmHg. Seven patients (four in Group I, three in Group II) died before recovering from the anesthetic. Of the 47 patients in Group II who survived, none had clinically apparent complications such as an epidural hematoma or meningitis from the intrathecal catheter. The mean aortic cross-clamp time was 58.6 +/- 30.5 minutes (mean +/- SD) in Group I versus 65 +/- 42.6 minutes in Group II. Twenty-three patients in Group I and 16 patients in Group II had a shunt to the distal aorta. To maintain a CSF pressure of < or = 15 mmHg in Group II, an average of 46.9 +/- 6.9 mL of CSF was withdrawn. Of the 45 survivors in Group I, 4 developed a spinal cord deficit; the number of patients with spinal cord deficit in Group II was 4 out of the 47 who survived.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1993

[Mesenchymal chondrosarcoma of the maxilla].

Mesenchymal chondrosarcoma is a variant that shows some peculiarities in comparison with classical chondrosarcomas. On the basis of a case report on a young man with a mesenchymal chondrosarcoma of the maxilla, the clinical symptomatology and diagnostics, morphological findings and actual therapy are discussed. In addition, problems of differential diagnosis are also discussed.

Adult↗
PubMed1993

Response to a single oral test of molybdenum stable isotopes for absorption studies in humans.

Two volunteer subjects were given orally enriched solutions of Mo-95 and Mo-96 respectively. Blood samples were drawn at various times following the tracer administration. The Mo-95 and Mo-96 content in plasma samples was determined by proton nuclear activation and the response to the single oral test of enriched stable molybdenum isotopes was determined. Assuming a simple two-open-compartment model where the first compartment is the gastrointestinal tract and the other is the plasma, an indicative value of the fractional intestinal absorption for the two subjects is given. The feasibility of direct quantitative measurements of Mo intestinal absorption by the double-tracer technique, using stable tracers, is evidenced.

Administration, Oral↗
PubMed1993

[Mycoplasma pneumoniae pneumopathies in children: clinical, biological and radiological study].

Clinical, radiological and biological features of 19 cases of serologically proven Mycoplasma pneumoniae pneumonia were compared with those of 21 cases of other types of pneumonia. Some clinical features were more frequent in M pneumoniae: patients older than 5 years, association with upper respiratory tract infection, skin rashes, acute course, unsuccessful treatment with penicillin. There were no specific radiological features. When compared with the complement fixation method, the serological diagnosis using agglutination technique appears to be more sensitive.

Acute Disease↗
PubMed1992

Homologies between the contiguous and fragmented rRNAs of the two Plasmodium falciparum extrachromosomal DNAs are limited to core sequences.

Plasmodium falciparum contains two extrachromosomal DNAs, a 6 kb linear element and a 35 kb circular DNA; both encode rDNA sequences. The 6 kb element rDNAs comprise fragments of both large and small subunit rRNAs. Comparison of these with corresponding rDNA sequences from the 35 kb DNA and E. coli show that sequences conserved between the three are largely confined to highly conserved core regions; in fact, most of the 6 kb rDNA sequences correspond to core regions. Both the 6 kb element and 35 kb rDNAs show less conservation to each other than to E. coli sequences, suggesting that the two extrachromosomal DNAs of P. falciparum are not closely related. The characteristics of the fragmented rRNAs from the 6 kb element suggest they are functional, possibly in mitochondrial ribosomes.

Animals↗
PubMed1992

Measurement of iron bioavailability by means of stable 54Fe and mass spectrometry.

Stable isotopes represent a useful tool for the assessment of biokinetic parameters in in vivo studies on humans. A procedure is described to evaluate the bioavailability of iron in pharmaceutical preparations by means of 54Fe as a tracer and mass spectrometry for the determination of time dependent changes in the isotope ratio of 54Fe/56Fe in red blood cells. Iron tablets with an increased portion of 54Fe were administered to iron deficient subjects and red cell iron utilization was used as a measure of iron bioavailability. Iron utilization was derived from changes in the 54Fe/56Fe ratio as evaluated by means of fast atom bombardment-mass spectrometry (FAB-MS) on processed blood samples. A good intraindividual reproducibility was observed for blood samples drawn at various times after application of the trial drug. Figures for bioavailability and its interindividual variations were in the range expected from comparable studies on similar iron preparations using radioiron as tracers. The results obtained show that quantitative data of bioavailability from pharmaceutical iron preparations may be obtained without radiation exposure of the subjects investigated.

Administration, Oral↗
PubMed1992

Changes of erythropoietic and storage iron components in certain clinical situations as evaluated by ferrokinetic investigations.

A method is described for the quantitative analysis of in vivo organ measurements of 59Fe activity in ferrokinetic investigations. The time-activity curves obtained by sequential surface monitoring over sacrum, liver and spleen can be resolved quantitatively into their different components contributing to the recorded count rate. The analysis is performed in three steps: (1) Count rate contributions from activity in other organs and from scattered radiation from regions outside the organ under investigation are corrected. (2) Distinction is made between radioactivity uptake of the tissue and radioactivity contained in the perfusing blood. (3) The resulting net organ activity is then further resolved into an erythropoietic and a storage iron component by use of a computer program (SAAM-27) and assuming a compartmental model for internal iron exchange. The method was tested in three groups of patients with different haematological disorders and in normal controls. Characteristic patterns of the parameters are found for different diseases and the results correlated well with the clinical findings. It is concluded that in vivo organ measurements of 59Fe activity, when performed and analysed with sufficient care, can provide an insight into the dynamics of the iron exchange that is taking place in an organ. This analytical approach may improve the diagnostic predictions of ferrokinetic investigations.

Erythropoietin↗
PubMed1992

T-cell-dependent immunity and thrombocytopenia in rats infected with Plasmodium chabaudi.

Normal, splenectomized, and athymic Fischer rats were infected with Plasmodium chabaudi. In normal rat infections, acute-phase infection resolved rapidly and completely. In splenectomized rats, infection resulted in high parasitemia and ultimately death. In nude rats, parasite growth was reduced compared with normal rats, and a persistent parasitemia (between 20 and 45%) was observed for several months. Complete resolution of the infection was achieved after adoptive transfer of T lymphocytes, even when transfer occurred during the course of infection. These results indicated that an acquired, T-lymphocyte-dependent immunity was necessary for the complete recovery observed in normal rats. In normal rats, thrombocytopenia and splenomegaly occurred during infection. By contrast, in nude rats, both of these pathological manifestations were only observed after thymus grafting. Thrombocytopenia was also absent in the splenectomized animals. Despite an increase in platelet-associated immunoglobulin levels during the infection, thrombocytopenia was not transferred by injection of infected rat serum to normal recipients. It has been concluded that the nude rat infection can be regarded as a novel and useful model for studying the T-cell-dependent effector and pathological mechanisms and to investigate the anti-P. chabaudi immune response.

Animals↗
PubMed1992

Effect of recombinant human erythropoietin on iron balance in maintenance hemodialysis: theoretical considerations, clinical experience and consequences.

Iron deficiency is the main reason for insufficient response to rEPO therapy. Serum ferritin and transferrin saturation give valuable information on storage iron and iron transport. Iron demand for correction of anemia can easily be estimated after HCT (vol%) x average blood volume (dl) = mg iron. Inadequate iron supply of the bone marrow in the presence of sufficient storage iron in the RES develops frequently under rEPO, possibly explaining the improvement of bone marrow response to rEPO by concomitant intravenous iron supply. The reasons of functional iron deficiency are still speculative.

Anemia↗
PubMed1992

Tattooing and high-risk behaviour among drug addicts.

One hundred and seventy-five patients treated at the drug dependence outpatient ward of the Psychiatric University Clinic of Vienna were investigated in February 1990 using a standardized questionnaire which included questions concerning tattoo behaviour. The tattooing procedure, often carried out in prison and employing unsterile equipment, is a possible way of HIV-1 transmission. It is recommended that the fragmentary legislation in Austria be rewritten and made more effective. According to a ministerial order only medical doctors are allowed to procure a licence for tattooing as it is an invasive procedure. Therefore no licensed tattooing establishments controlled by public health offices exist. Their legal existence would guarantee a hygienic standard and reduce the danger of infection.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Stable isotopes for determining biokinetic parameters of tellurium in rabbits.

We have compared the use of stable and radioactive isotopes for determining the concentration of tellurium in body fluids of animals and man, specifically in the blood plasma of rabbits. Particular effort has been devoted to developing a sample-processing technique that allows the total amount of tellurium and isotope ratios to be measured by graphite furnace atomic absorption spectrometry (GFAAS) and secondary ion mass spectrometry (SIMS), respectively. The procedure employed in the SIMS analysis is discussed in detail. Investigations on the plasma clearance and the fractional intestinal absorption were carried out on four rabbits. Tracer solutions containing stable tellurium enriched in 124Te or 126Te and radioactive tellurium (121mTe or 123mTe) were administered by gavage and/or intravenously. Blood samples were drawn during the first 2 days after application. The activity of the separated plasma was measured by standard gamma ray spectrometry. After wet ashing and solvent extraction with MIBK the samples were analyzed for stable tellurium. A detection limit of 1 ng/mL of plasma could be achieved with GFAAS. For SIMS analysis the processed samples were deposited on high-purity graphite backings. Reliable isotope ratios could be determined with sample fractions containing 1 ng of tellurium or even less. The results obtained by applying stable isotopes were found to be in good agreement with the data achieved by using radioactive tracers. Studies on the intestinal absorption and the metabolic behavior of tellurium in human volunteers may thus be performed with stable isotopes.

Animals↗
PubMed1991

Optimized conditions for electrotransformation of bacteria are related to the extent of electropermeabilization.

Electropulsation is a simple and efficient way to introduce cloned genes into a variety of cell types, even with walled species. In the case of bacteria, we observed no direct correlation between survival rate and transformation yield. In the present work, we show that the yield of transformation is directly related to the level of the electric-field induced level of cell permeabilization. From experiments on Escherichia coli, it was confirmed that the extent of associated ATP leakage was a reliable assay. This approach was extended to other strains, such as Salmonella typhimurium, which to date had not been electrotransformed by plasmids.

Adenosine Triphosphate↗
PubMed1991

Sharing spoons: a risk factor for HIV-1 infection in Vienna.

Sharing of needles and syringes plays a central role in HIV-1 transmission among intravenous drug users (IVDUs). There have been several suggestions to protect the injecting population from further harm, but focused mainly on the use of sterile needles and syringes as well as information about safer sexual behavior. This study examined a total of 366 IVDUs at the drug dependence out-patient ward of the Psychiatric University Clinic of Vienna. HIV-1 antibodies were found in 29.7% (58) in 1989 and in 26.9% (42) in 1990. The results show that in 1989 14% and in 1990 5% IVDUs who never shared needles or syringes or other drug paraphernalia were found to be HIV-1 positive. In spite of the high information standard among Viennese drug addicts on risk reduction, the underestimated co-factors during drug administration might be responsible for a further HIV-1 transmission. Educational interventions on this subject should address even IVDUs who do not share needles and have adjusted to 'safer sex' practices.

Austria↗
PubMed1991

Assessment of iron availability using stable 54Fe.

This paper describes a method of quantitatively assaying the bioavailability of orally administered iron in order to promote haemoglobin synthesis in iron deficiency anaemia. The non-radioactive tracer substance 54Fe was employed. An experimental iron deficiency model was tested in 18 healthy male volunteers. The trial design made it possible to assess intestinal absorption and efficacy of iron substitution. The iron deficiency was experimentally induced by weekly phlebotomy. Two commercially available iron preparations with different rates of iron release were investigated at a dosage of 150 and 160 mg Fe2+ daily, respectively. In the first seven days of treatment, both preparations were administered in 54Fe-labelled form. Afterwards, iron substitution was given with the commercially available preparations. Measurements were made of erythrocyte utilization of 54Fe and plasma iron tolerance curves at the beginning of the periods in which the 54Fe-labelled product and the commercially available preparation were administered, and of haemoglobin and serum ferritin concentration curves over three months. The mean utilization of the iron administered was virtually identical for the two preparations (23 and 22%, respectively). Likewise, there was no difference with respect to the average daily increase in haemoglobin concentration in the blood (1.5 g 1-1). There was also no significant difference with respect to serum ferritin concentration curves. In contrast, the two preparations differed markedly with respect to the plasma iron tolerance curves. This suggests that evaluation of plasma iron tolerance curves alone is not suitable for comparative assessment of the therapeutic value of orally administered iron preparations.

Administration, Oral↗
PubMed1991

A greater than 200 kb deletion removing the entire beta-like globin gene cluster in a family of Irish descent.

We describe a new deletional form of gamma delta beta-thalassemia segregating in two generations of a family of Irish descent. Affected family members present with a beta-thalassemia minor phenotype, normal Hb A2 and Hb F levels. Genomic blotting analyses on DNA from affected family members show heterozygosity for a large deletion beginning at least 15 kb upstream of the 5' endpoint of the gamma delta beta-thalassemia-1 deletion, extending through the entire beta-like globin gene cluster, and continuing for at least 10 kb beyond the 3' endpoint of the deletion associated with the Spanish form of delta beta 0-thalassemia. This deletion is among the largest described so far, and removes at least 205 kb encompassing the entire beta-like globin gene cluster on chromosome 11.

Adult↗