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Biomedical subjects

R Voss

Publications and source records attributed to R Voss.

At least 37 records · Page 2Linked to original sources
PubMed1998

[Disorders of microcirculation in coronary heart disease].

Disturbances of microcirculation in coronary artery disease can be seen in the presence of critical stenosis of epicardial coronary arteries, as a result of endothelial dysfunction in the absence of significant stenosis or during recovery of ischaemic myocardium after successful angioplasty of stenosed or occluded coronary arteries. Diagnostic methods are morphologic/morphometric analyses, measurement of the global coronary reserve, measurement of the regional coronary microcirculation (scintigraphy, positron emission tomography) and laboratory analysis of haemorheological alterations (plasma, erythrocytes, leucocytes). After successful angioplasty, normalisation of glutamate extraction rate takes three to six months. In patients with unstable angina, changes in plasma viscosity, erythrocyte aggregation and neutrophil activation occur. Neutrophils are activated after successful angioplasty in acute myocardial infarction and even after elective angioplasty (when measured in the coronary sinus). Therapeutic improvements of disturbed microvascular flow can be obtained by increasing perfusion pressure (by revascularisation, nitrates, calcium antagonists, physical training), by improving the fluidity of the blood and by reducing the extravascular component of coronary vascular resistance (by antihypertensive treatment).

Angina Pectoris↗
PubMed1998

Long-term follow-up after direct percutaneous transluminal coronary angioplasty for acute myocardial infarction.

OBJECTIVES: The purpose of this study was to analyze long-term follow-up information over several years from consecutive, unselected patients treated with direct percutaneous transluminal coronary angioplasty (PTCA) for acute myocardial infarction (MI). BACKGROUND: Direct PTCA is often used in patients with acute MI. Short-term results are favorable. However, there is less information available on long-term observations over several years in these patients. METHODS: A total of 416 consecutive and unselected patients with acute MI underwent direct PTCA. Survival of the acute infarct phase was 94.2%; the remaining 392 patients--the study population-were discharged and followed for 3.3+/-1.4 years. Mortality as well as cardiac events and reinterventions are reported. Clinical variables assessed at the time of discharge are submitted to statistical analysis to detect potential risk factors. RESULTS: Total cumulative mortality in the first year was 10% for the entire group and 6% for patients not presenting in cardiogenic shock. Mortality after discharge was 4.6% in the first year and dropped to <4% per year thereafter. Reinterventions after discharge were required in 16% in the first year and in <4% per year in years 2 to 4. Poor left ventricular ejection fraction (<35%), three-vessel disease and advanced age (> or =75 years) were long-term risk factors for total mortality after direct PTCA. CONCLUSIONS: The clinical benefit of direct PTCA for acute MI is maintained during follow-up with respect to mortality. However, reinterventions for restenosis or de novo stenosis are often required (10% to 20%). Although few in number (<10%), patients with severely impaired left ventricular function continue to have a poor prognosis.

Adult↗
PubMed1997

[Facial fractures. A life style disease among young men?].

Interpersonal violence is often initiated by offensive verbal and visual expressions. Physical violence will therefore often be directed towards the face of the opponent. A retrospective analysis of 1,273 maxillofacial fractures at the University Hospital in Tromsø during the period 1987-95 showed a steady occurrence of cases. A prospective study of 162 maxillofacial fractures at Ostfold Central Hospital in 1993 was compared with the material from Tromsø. In both studies half of the patients were young men. Males aged 15-29 years were involved seven to eight times more frequently than the rest of the population. Violence among young men under the influence of alcohol was the predominant cause of the fractures. Young male assault victims often started the fight or actively encouraged it. "Participant" is often a more appropriate term than "victim". Some of those involved relapse into a lifestyle inflicting recurrent maxillofacial fractures. Domestic violence involving females is often disguised as accidents. Alternative methods of solving conflicts should replace the offending behaviour to prevent maxillofacial fractures.

Adolescent↗
PubMed1997

[New studies, new trends: directional coronary atherectomy].

Despite theoretical advantages of Directional Coronary Atherectomy (DCA) vs. PTCA, the first two controlled studies comparing both methods, the Coronary Angioplasty Versus Excisional Atherectomy Trial (CAVEAT), and the Canadian Coronary Atherectomy Trial (CCAT), showed no clinical benefit of DCA, A second generation of trials, the Optimal Atherectomy Restenosis Study (OARS) and the Balloon versus Optimal Atherectomy Trial (BOAT), designed to optimize DCA with the use of 7F devices and adjunctive PTCA revealed lower angiographic restenosis rates compared to CAVEAT. In addition, the preliminary follow-up results of BOAT, presented by Donald S. Baim in Birmingham in August 1996, showed a 20% reduction of angiographic restenosis after DCA compared to PTCA. There was no association between post-procedure CK-MB elevation in the DCA group and late mortality. These results may further expand the application of DCA to clinical routine, whereas this procedure still has specific indications like treatment of ostial and bifurcation lesions and atherectomy in future may be the treatment of choice for restenosis in coronary stents.

Angioplasty, Balloon, Coronary↗
PubMed1997

[Early and long-term results of direct PTCA in patients with acute myocardial infarct].

A review of the literature suggests that direct PTCA for acute myocardial infarction is indicated and feasible in 90-95% of unselected, consecutive patients; direct PTCA is reported to be successful in > 90% of procedures. This results in a hospital mortality of 3-7% for unselected patients and a 4% re-infarction rate. A recent meta-analysis of direct PTCA vs i.v. thrombolysis in patients with acute infarction demonstrates a lower mortality after PTCA (4.4% vs 6.5%, p = 0.02) as well as lower mortality/re-infarction rate (7.2% vs 11.9%, p < 0.001). Mortality in the 1st year after discharge is < 5% with about half of the fatalities being due to cardiac causes. Patients presenting with or developing cardiogenic shock in the acute infarct phase experience a 20-50% acute mortality. Mortality rests at < 10% in these patients in the first year after discharge. In conclusion, (1) direct PTCA is feasible without additional risks in patients with acute myocardial infarction, (2) angiographic and clinical success rates of direct PTCA are favorable and superior to i.v. thrombolysis in the hands of expert operators, and (3) referral to an institution providing the option of immediate, direct PTCA must be considered in the patient with acute infarction but contraindication(s) to i.v. thrombolysis.

Angioplasty, Balloon, Coronary↗
PubMed1997

[Current aspects of thrombolytic therapy in unstable angina pectoris].

In the last years, several studies addressed the role of the different antithrombotic therapeutics in unstable angina pectoris. Acetylsalicylic acid still is the standard treatment reducing the rate of death and myocardial infarction by 50% in the first six months. Ticlopidin has no clinical effect in the first six days and therefore is not suited for treatment in the acute phase. Unfractionated heparin has an additional favourable effect when added to aspirin. Low molecular weight-heparin is at least as effective as UF-heparin. Direct thrombin-inhibitors (hirudin, hirudin-analoga) seem to be comparable to UF-heparin. Plasminogen-activators should not be given in unstable angina, as they show a tendency to worsen the clinical outcome. GP IIb/IIIa-antagonists (antibodies, synthetic antagonists) significantly improve the clinical effects of aspirin. When combined with a reduced dose of heparin, their favourable effect remains unchanged, while bleeding complications are reduced to a minimum.

Angina, Unstable↗
PubMed1996

Hemostatic abnormalities and the severity of illness in patients at the onset of clinically defined sepsis. Possible indication of the degree of endothelial cell activation?

OBJECTIVE: To find out whether changes within the hemostatic system are related to the severity of illness and organ failure in patients at the onset of clinically defined sepsis and to find some indications for the contribution of endothelial cell activation or perturbation to the patient's status. The following measurements were undertaken: Acute Physiology and Chronic Health Evaluation (APACHE) II score, multiple organ failure (MOF) score, plasma levels of thrombin-antithrombin III complexes (TAT), antithrombin III (AT III), protein C antigen, factor XII, and plasminogen activator inhibitor type 1 antigen (PAI-1), neopterin, and interleukin 6 (IL-6). DESIGN: A prospective case series study. SETTING: Intensive care unit (ICU) of the Department of Internal Medicine, Justus Liebig University, Giessen, Germany. PATIENTS: 28 consecutive patients (11 females, 17 males; mean age 58 years) with clinically defined sepsis. Eleven patients were admitted from the surgical ICU (9 after elective surgery, 2 after trauma surgery). The operations were done 1-26 days (mean 14 days) prior to the onset of sepsis. MAIN RESULTS: At the onset of sepsis we found elevated plasma levels of TAT, PAI-1, neopterin, and IL-6, and lowered plasma levels of AT III, factor XII, and protein Cantigen. Neopterin, PAI-1, IL-6, and factor XII showed a statistically significant correlation with the APACHE II score. The MOF score is significantly correlated with IL-6 and neopterin. The extent of hemostatic abnormalities was related to increasing levels of IL-6. CONCLUSIONS: Clinical evidence of a septic process is most likely to be preceded by activation of the hemostatic system, the vascular endothelium, and the monocyte/macrophage system. IL-6 may have a regulatory function for hemostasis in inflammation. Laboratory monitoring could be helpful in deciding whether to start early intensive therapy in patients at risk for sepsis.

Adult↗
PubMed1996

Structure and function of learning flights in ground-nesting bees and wasps

Bees and wasps perform systematic flight manoevres when they leave their nest or a foodplace, during which they acquire or update their visual memory of the goal location. In a typical learning flight, the insect backs away from the goal in a series of arcs that are roughly centred on the goal. The mean rate of turning is rather constant and tends to balance the angular speed at which the arc is described. As a result, the insect views the goal at relatively fixed retinal positions in its left and right visual field, depending on flight direction. The general direction in which the insect backs away from the goal and the transition from one arc segment to the next are influenced by the local scene and by compass cues. Insects returning to the goal repeat some of the flight manoeuvres of their preceding learning flights. Their orientation in space and the retinal positions at which they view nearby landmarks are similar. One important function of learning flights appears to be the acquisition of visual depth information. We review the consequences of the structure of learning flights for visual information processing and discuss how they may relate to the acquisition of a visual representation and the task of pinpointing the goal.

Journal Article↗
PubMed1995

[Endemic sprue: its first diagnosis based on bleeding complications].

HISTORY AND CLINICAL FINDINGS: A 47-year-old man without previously known illness was admitted to hospital because of acute haematomas in the legs: the history revealed no cause. The pale-looking patient reported having large and foul-smelling stools once or twice daily. There were large haematomas and swellings on both legs. His general and nutritional state was reduced. "Bleeding of unknown origin" was suspected at this time. INVESTIGATIONS: Haemoglobin concentration was 5.6 g/dl, while iron was normal and ferritin reduced. Quick value was below 5%, activated partial thromboplastin time prolonged to 180 s. Vitamin A and E concentrations were reduced; coumarin derivatives were not demonstrated in blood. Abdominal ultrasonography showed clearly thickened intestinal walls. TREATMENT AND COURSE: Four units of erythrocyte concentrate were immediately administered, together with 2000 IU factors II, VII, X and anti-haemophilic factor B (PPSB), and 10 mg vitamin K intravenously. As intestinal malabsorption was suspected, a vitamin A absorption test was performed: it indicated malabsorption. Upper intestinal endoscopy showed coeliac disease, as did a biopsy. The patient's state quickly improved after he had been given vitamins A, D, E and K and put on a gluten-free diet. CONCLUSION: Coeliac disease can take a clinically unremarkable course for a long time and may finally become manifest through an isolated abnormality, such as bleeding.

Acute Disease↗
PubMed1995

Smith-Lemli-Opitz syndrome diagnosed by using time-of-flight secondary-ion mass spectrometry.

We describe a rapid and sensitive method involving time-of-flight secondary-ion mass spectrometry (TOF-SIMS) for specific laboratory diagnosis of the Smith-Lemli-Opitz syndrome, which is characterized by massive (approximately 1000-fold) accumulation of the biosynthetic cholesterol precursor 7-dehydrocholesterol. Minute amounts of blood (1-50 microL) were extracted with n-hexane, and aliquots were analyzed by TOF-SIMS. 7-Dehydrocholesterol and its isomers were detected at 491.3 mass units ([M + 107Ag]+) and cholesterol at 495.3 mass units ([M + 109Ag]+). Quantitation of 7-dehydrocholesterol and cholesterol was achieved after saponification and addition of stigmasterol as internal standard. Whereas 7-dehydrocholesterol and isomeric dehydrocholesterol were not detectable in controls, the patients revealed concentrations ranging between 0.84 and 1.25 mmol/L. Comparison with results obtained by gas chromatography indicated that quantitation by TOF-SIMS yielded the sum of 7-dehydrocholesterol, isomeric dehydrocholesterol II, and sterol III, the latter two also being increased in the patients. Consistent with quantitation by gas chromatography, the cholesterol concentrations in the patients ranged between 1.54 and 2.12 mmol/L (controls: 6.10 +/- 1.37 mmol/L).

Cholesterol↗
PubMed1994

[Not Available].

Explore the source record for details and available documents.

Craniology↗
PubMed1993

In vitro and ex vivo effects of aspirin in patients on a low-dose aspirin therapy.

In 19 patients on a low-dose aspirin therapy with 100 mg/d, an insufficient effect of aspirin was observed in five patients (aggregations induced by arachidonic acid and collagen, thromboxane B2-formation in serum and after collagen). Aspirin added in vitro increased the inhibition to a degree comparable to that seen in the other 14 patients, i.e. the insufficient effect could be due to a lack of compliance or to a reduced availability of the drug. In another 20 patients there was a good inhibitory effect of aspirin; additional aspirin did not increase the inhibition of arachidonic acid-induced aggregation and serum-thromboxane B2, but slightly increased collagen-induced aggregation and thromboxane B2 formation. The effect was the same, whether the aspirin was given in vivo or added in vitro.

Adult↗
PubMed1992

Phytohemagglutinin gene expression during seed development of the runner bean, Phaseolus coccineus.

The expression of phytohemagglutinin (PHA) genes was studied in various tissues during the development of the seeds of Phaseolus coccineus cv. Hammond's Dwarf Scarlet by means of northern hybridization and reverse transcription polymerase chain reaction (RT-PCR). The expression is highly development-dependent, starting in the late stage (cotyledons begin to fill the endosperm cavity, i.e. 17 to 24 days after pollination), and tissue-specific. The highest levels of PHA-mRNA are found in the cotyledons (at a very late stage), much lower levels in the embryo axis. Very low levels could be detected in earlier stages of the endosperm, the integument, the funiculus, and probably also in the embryo suspensor. Some PHA mRNA was found in the cotyledons of dry seeds, indicating the presence of undegraded transcripts in mature seeds.

Base Sequence↗
PubMed1992

How often is dysplasia diagnosed by biopsy or smear examination? Application of a maximum likelihood based method to the assessment of detection rates in the nasal mucosa of nickel workers.

In view of the known increased risk of nasal carcinoma and the high prevalence of dysplastic lesions of the nasal mucosa among nickel workers, regular screening for the existence of possibly precancerous dysplastic lesions is offered to workers in a Norwegian nickel refinery. Unfortunately, available sampling techniques do not allow the identification of all subjects in whom dysplastic changes are present. Independent histological and cytological (brush cytology) diagnoses, obtained for each of a group of 90 workers, have been used to estimate, by a maximum likelihood method, the probabilities that existing dysplastic lesions will be detected by each of these two screening methods. In the group studied, cytology performed rather less well than histology in unambiguously detecting dysplasia. However, when cytological specimens showing irregular (possibly dysplastic) epithelial cells were grouped with those showing clear dysplastic changes, detection probabilities were estimated at 0.52 by histology and 0.57 by cytology. Detection probabilities were estimated to be higher among subjects with a previously known history of dysplasia, particularly by histology (P < 0.01), probably due to larger dysplastic areas. In view of both its greater facility and speed of sampling, and its greater acceptability, brush cytology may be preferable to biopsy sampling for the screening of large numbers of workers at risk.

Biopsy↗
PubMed1991

Corrected TMJ tomography: effectiveness of alternatives to SMV tracing.

An axial (SMV) radiograph has been widely used to determine parasagittal head position in TMJ tomograms. The purpose of this study was to investigate the efficacy of alternative anatomic methods for patient positioning in TMJ tomograms. The positioning methods studied included (1) rotation of the patient's head toward the film plane on the basis of the condylar orientation as determined by an SMV radiograph, (2) arbitrary rotation of the patient's head 20 degrees toward the film plane, (3) placement of the zygomatic arch parallel to the film plane, and (4) positioning of the posterior occlusal plane parallel to the film plane. Statistical analysis of the accuracy of the positioning techniques revealed no differences in the SMV, the zygomatic arch, and the arbitrary 20 degrees positioning. Aligning the posterior occlusal plane did not adequately align the mandible into a favorable radiographic position.

Analysis of Variance↗
PubMed1991

[Clinical behavior of NPM dental alloys after several years of intraoral service].

179 patients from the University Dental School of Cologne with 437 crowns and bridges cast of base metal alloys (Wiron 77, Wiron 88, Microbond NP2) were evaluated after clinical exposure between two and six years. Symptoms indicating corrosion, allergic or toxic reactions were not found. Cracking of ceramometal veneers occured in 2.8%. The survival rate of the examined crowns and bridges was 95% for those cast of Wiron 88 after four years of service and 97.7% for those of Wiron 77 after six years.

Corrosion↗