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Biomedical subjects

R Marx

Publications and source records attributed to R Marx.

At least 55 records · Page 3Linked to original sources
PubMed1995

CareBase: a reference base for nursing.

Due to the lack of generally accepted nursing classifications and standards in Germany the introduction of nursing information systems for planning and documentation of care is a very time consuming process since the classifications and standards must be defined locally to adjust the systems. At the University Hospital Freiburg a nursing reference system was developed to collect this knowledge, make it available for easy reference and as a source usable for the initialisation of nursing information systems to be installed in the future.

Humans↗
PubMed1994

Complete sequence of 3'-untranslated region of Tau from rat central nervous system. Implications for mRNA heterogeneity.

Tau is a family of microtubule associated proteins, heterogeneous in molecular weights, which are expressed specifically in neurons. Tau is encoded by a single gene, while its transcript undergoes a complex and regulated alternative splicing, giving rise to several mRNA species that migrate on Northern blots at approximately 6 and 2 kb. In this report we characterize a full size transcript of tau mRNA from rat brain and demonstrate that it contains 5203 nucleotides (not including exon 2 and 3), which correlates well with the exact size of the transcript as analyzed by Northern blot using RNA standard size markers. The full length of the 3'-untranslated region contains 3848 bp and includes two polyadenylation signals which may yield the two size transcripts in the central nervous system. The first polyadenylation signal is located in the retained intron 13/14 and the second polyadenylation signal is 19 nucleotides before the poly(A) tail. Unspliced intron 13/14 was detected in all RNA preparations tested, including RNA from different ages and different regions of rat brain, RNA from dorsal root ganglia and from undifferentiated and differentiated PC12 cells. In none of the above tissues and cells was a spliced transcript lacking intron 13/14 detected.

Amino Acid Sequence↗
PubMed1994

Late endogenous potentials in three-tone experiment in short- and long-term abstinent alcoholics.

Information processing (and cognitive ERPs as their concomitants) has been observed to be disturbed in chronic alcoholics and to recover with sustained abstinence. However, some specific components of ERPs appear to remain significantly decreased in long-term abstinent alcoholics. Using a longitudinal design we investigated the effect of abstinence and relapse on P300 and Late Slow Wave. P300 was evoked by a three-tone paradigm, which results in a two-stage process for evaluating and classifying stimuli. The amplitude of P300 in short-term abstinent alcoholics was reduced significantly and recovered with time of abstinence at least partly. In alcoholics abstinent for eight months the mean amplitude was lower than of the control group, but this difference failed to be significant. The long latency of the positive peak at about 600 ms seems to reflect delayed information processing in alcoholics, revealed by two-stage processing. This component arises later in alcoholics whether they stay abstinent or not.

Adult↗
PubMed1994

[Principles of duplex ultrasound diagnosis of the internal thoracic artery].

Because of its better long term patency the internal thoracic artery has become the conduit of choice for myocardial revascularization. Thirty healthy young volunteers were investigated to prove the suitability of the duplex system for investigating the internal thoracic artery. The mean systolic peak flow velocity was 1.15 m/s in the proximal vessel decreasing to 0.55 m/s in the peripheral course of the artery. Mean internal thoracic artery diameters at the origin were calculated as 2.18 mm for the left and 2.43 mm for the right internal thoracic artery. The flow curves represent those of elastic-type vessels, whereas in a small number resistance curves occurred representing the muscular type. The combination of two-dimensional B-mode and Doppler unit allows visualization of the internal thoracic artery and assessing the flow velocities within the vessel. Ultrasonic duplex scanning is a noninvasive diagnostic tool for investigation of the internal thoracic artery.

Adult↗
PubMed1994

Duplex sonography of the internal thoracic artery. Preoperative assessment.

Ultrasonic duplex scanning was used to examine 211 internal thoracic arteries. The investigating vessels were classified as normal, abnormal, and occluded. The results of the duplex examination were compared with angiography as the reference method. The diameter measurements showed virtually no differences between the two methods. Normal internal thoracic arteries showed a continuous decrease of the systolic flow velocities from proximal to distal and a narrow to moderate spectral flow curve, whereas arteries classified as abnormal showed a velocity profile distinct from that--in particular, no decrease of the systolic peak velocities and an increased spectral broadening during systole with peak frequencies greater than 4 kHz at 60 degrees (> 1.2 m/sec). In occluded vessels no flow could be detected. The majority of changes were found in the proximal part of the internal thoracic artery. All lesions were detected by duplex sonography. Six normal vessels were misjudged as abnormal by the duplex method. The sensitivity, specificity, and accuracy of duplex sonography compared with angiography as the reference method were 100% (95% CI, 74.4% to 100%), 96.9% (95% CI, 93.2% to 98.8%), and 97.2% (95% CI, 93.6% to 98.8%), respectively. Duplex sonography is a reliable, noninvasive technique for the preoperative assessment of the internal thoracic artery. It allows the detection of potential atherosclerotic changes in the internal thoracic artery and the assessment of adequacy of caliber and flow.

Adult↗
PubMed1994

[The mechanical loading capacity of new all-ceramic crown and bridge materials].

The present contribution presents the fracture toughness KIc, the bending strength and the splitting tensile strength of the recently developed all ceramics Cerec, Dicor, Duceram, IPS-Empress, Flexo-Ceram, Hi-Ceram, In-Ceram, LFC, Mirage (I, II), Optec HSP, Syntho-Ceram and Vitadur. The toughness of those materials suitable for crowns and bridges were also tested with the help of the "Normkronentest" on incisor and canine abutments made from natural teeth or Wiron alloy. As a consequence of our investigations we propose a differentiation into three classes of toughness: class I (fracture toughness up to 2.0 MPa*m1/2, fracture stress up to 100 MPa) consists of the leucite, mica or whisker strengthened ceramics Cerec, Dicor, Duceram, IPS-Empress, Flexo-Ceram, LFC, Mirage (I, II), Optec HSP and Vitadur Alpha, N. Dicor and Optec HSP are at the upper boundary. Class II (fracture toughness up to 3.0 MPa*m1/2, fracture stress up to 150 MPa) consists of the aluminium oxid strengthened ceramics Hi-Ceram, Syntho-Ceram and Vitadur N Kern. Class III (fracture toughness more than 3.0 MPa*m1/2, fracture stress more than 150 MPa) up to now consists only of the infiltration ceramics In-Ceram.

Ceramics↗
PubMed1993

Sociocultural aspects of blindness in an Egyptian delta hamlet: visual impairment vs. visual disability.

Through ophthalmological exams, structured interviews and participant observation, this study examines the experience of blindness in rural Egypt, and finds that villagers' subjective assessments of their vision differ substantially from ophthalmic measurements of their vision. Individuals with profound visual loss remain independent in their daily activities and contribute to their families' subsistence. While they may agree that they have "weak eyesight," they do not perceive themselves to be disabled. Stigmatizing attitudes that the blind are completely dependent and unable to fulfill their social roles further encourage those with decreased vision to deny the extent of their visual loss.

Adolescent↗
PubMed1992

The effect of corrosive environment on the porcelain-to-metal bond--a fracture mechanics investigation.

Microcracks, flaws, and voids inside a metal-porcelain restoration may cause the restoration to fracture in service. Such cracks result in the concentration of stresses. The dynamic nature of the stresses due to mastication promotes crack growth. In addition, corrosive components of the oral environment enhance the growth rate. In the present investigation, fracture mechanics has been used to analyze the in vitro resistance to fracture of the porcelain-fused-to-metal restoration. The risk of a clinical failure of porcelain-fused-to-metal decreases with enlarged crack resistance (increasing work of fracture). The work of fracture represents an average of the energy for initiation and propagation of a crack through the interface separating porcelain and metal. This work also indicates a material's ability to stop a crack once it is moving. This study utilized the three-point bending test for the crack resistance measurement, and investigated one palladium and five base metal alloys. Corrosive components of the oral environment and the details of firing were of crucial importance for long-term bond stability.

Corrosion↗
PubMed1992

Human cell culture studies with dental metallic materials.

The compatibility of cast non-alloyed titanium and eight dental castable alloys (precious, low noble, non-precious) was determined by means of human primary oral fibroblasts derived from the attached gingiva and the periodontium. Furthermore, cast non-alloyed Ti was tested in a human permanent cell culture (MOLT 4). All investigated metallic materials showed cytotoxic properties in primary cultures. The differences in cytotoxicity between the various materials were statistically significant. The best results were found for one noble alloy and for non-alloyed titanium, whereas all non-precious alloys almost completely inhibited cell growth. The cytotoxic potential of the investigated materials might contribute to the irritating effect of dental cast restorations adjacent to the gingiva and the periodontium.

Biocompatible Materials↗
PubMed1992

Combined two-dimensional and Doppler echographic examination of internal mammary artery grafts from the supraclavicular fossa.

The noninvasive examination of internal mammary artery grafts is gaining importance with the increasing use of this vessel in the surgical treatment of coronary atherosclerosis of the left anterior descending artery. We studied 36 patients (37 internal mammary artery grafts) with combined two-dimensional and pulsed Doppler echography from the supraclavicular fossa. Adequate visualization and Doppler signals were obtained in 95% of arterial grafts. Twenty-four grafts leading to an area without evidence of old myocardial infarction or ischemia and 10 grafts leading to an area of old myocardial infarction but without evidence of ischemia on exercise showed a significant decrease of the peak systolic velocity and of the peak systolic velocity/peak diastolic velocity ratio as compared to the controls, which consisted of the contralateral internal mammary arteries in situ. One patient with a distally subtotally occluded mammary artery graft had a flow pattern different from the other bypassed mammary arteries. It seems that combined two-dimensional and pulsed Doppler echography is a useful method to evaluate the functional status of internal mammary artery grafts.

Adult↗
PubMed1991

[Studies on the bond strength of various titanium-ceramic base materials].

The present contribution presents the results of a study comparing the bond strength of Ohara Titan Bond (Tanaka, Bad Homburg), Vita Titankeramik (Vita, Bad Säckingen) and Duceratin Experimental Titankeramik (Ducera, Rosbach) fused to titanium with that of Vita VMK 68 fused to Wiron 88. For the measurement of the bond strength we utilized the three point bending test of fracture mechanics.

Corrosion↗
PubMed1991

[Mechanical strength of ceramic materials for fusing on titanium restorations].

Bending, splitting tensile, and bond strengths of four ceramic systems for veneering titanium frameworks as well as the fatigue strength of the complete metal-ceramic crown were evaluated. The mechanical properties of ceramo-metallic systems are comparable with those of conventional dental ceramics. A slight increase in bending, tensile, and bond strengths when using higher firing temperatures was observed, although this did not result in an increased endurance strength of the complete system.

Crowns↗
PubMed1991

[System for intraoral repair of ceramic blends--an in vitro study of adhesive strength].

We investigated composite repair systems for crown facings which consisted in principle of a silane primer, of an unfilled Bis-GMA bonding agent and of a filled Bis-GMA resin. The in vitro investigations revealed that under oral conditions the longterm durability of the bond strength is still unsufficient, unless care is taken that the debris layer which is caused by mechanical treatment has been removed.

Adhesiveness↗
PubMed1991

[Possibilities for the detection and monitoring of children and adolescents with hypertension].

Blood pressure measurements have been taken for ten years or more on the basis of a standard programme as part of the paediatric mass screening, starting with the second medical examination for school entrance. They have now become an integral component of this checkup routine. The following recommendations are made for a revised prophylactic examination programme: enlargement of case history questionnaire on arterial hypertension, maintenance of present valid norms and recommendations for medical attention in cases of high blood pressure risk, and blood pressure measurements for school entrants in grades 6 and 9.

Adolescent↗
PubMed1991

[Bond strength of etched In-Ceram(R) to tooth enamel].

Laminate veneers of porcelain may be suitable for the correction of enamel anomalies of incisors. They are, however, within the mouth subjected to high mechanical loads, aggressive humidity and abrupt temperature changes. Consequently high strength porcelain and a stable bond between the veneer and the enamel are mandatory. To prepare a retentive surface microscopic investigations reveal that etching of In-Ceram porcelain is less effective than etching of Biodent porcelain, which we investigated as a reference material. This is in accordance with the observed insufficient bond strength between In-Ceram porcelain and enamel. Therefore we conclude that under the environmental condition of the mouth In-Ceram porcelain, even if it is layered with Vitadur porcelain, can not be durably bonded to enamel at present.

Acid Etching, Dental↗
PubMed1990

Regulation of 1,25-dihydroxyvitamin D3 receptor gene expression by 1,25-dihydroxyvitamin D3 in the parathyroid in vivo.

1,25-Dihydroxyvitamin D3 (1,25(OH)2D3 dramatically decreases parathyroid hormone (PTH) gene transcription. We have now studied the effect of 1,25(OH)2D3 on the 1,25(OH)2D receptor (VDR) in the parathyroid in vivo. Rats were injected with 1,25(OH)2D3 and the parathyroid-thyroid tissue analyzed for PTHmRNA and VDRmRNA. 1,25(OH)2D3 (50 and 100 pmol ip) decreased PTHmRNA at 6 h with a maximum at 48 h (less than 4% of basal), whereas VDRmRNA was increased only after 6 h with a 1.7-fold increase at 24 h. VDRmRNA levels peaked at 25 pmol 1,25(OH)2D3 with a twofold increase. Serum calcium did not affect VDRmRNA. Parathyroid VDRmRNA ran at 2.2 and 4.4 kb, whereas duodenum VDRmRNA had a single band, all of which increased after 1,25(OH)2D3. Weanling rats on a vitamin D-deficient diet for 3 wk had a more intense 2.2-kb transcript, whereas vitamin D-replete rats had a more intense 4.4-kb band. Dispersed parathyroid-thyroid cells were separated by a flow cytometry (FACS) into a parathyroid cell peak containing PTHmRNA and a second peak with cells positive for thyro-globulin mRNA and calcitonin mRNA. VDRmRNA was concentrated in the parathyroid cell peak. In situ hybridization of parathyroid-thyroid and duodenum for VDRmRNA showed its localization to the parathyroid cells and the duodenal mucosa. Therefore, the VDRmRNA in the parathyroid-thyroid tissue represents predominantly parathyroid cell and not C-cell VDRmRNA which is also a 1,25(OH)2D3 target organ. The increased VDR gene expression in the parathyroid cell would amplify the effect of 1,25(OH)2D3 to decrease PTH gene transcription.

Animals↗