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Biomedical subjects

D Holtz

Publications and source records attributed to D Holtz.

11 recordsLinked to original sources
PubMed1999

[D-dimer determination in suspected deep venous thrombosis or lung embolism].

Cleavage of crosslinked fibrin by the fibrinolytic enzyme plasmin leads to the formation of fibrin degradation products, among them D-dimers. D-Dimer can easily be measured in plasma or in whole blood by means of monoclonal antibodies directed against epitopes of the D-dimer fragment. Elevated plasma levels of D-dimers are characteristic for patients with venous thromboembolism (DVT, PE), but occur also in patients with infectious diseases, malignant neoplasms and heart failure. Given the high sensitivity of ELISA D-dimer assays with respect to venous thromboembolism it is possible to reliably rule out DVT or PE when the plasma concentration of D-dimer is below the cut-off level. Thus, it is possible to rule out DVT in about 30% of outpatients with suspected venous thromboembolism by the measurement of D-dimer-concentration with a validated assay avoiding further diagnostic procedures.

Diagnosis, Differential↗
PubMed1997

Relationship between self-perceived stress and blood pressure.

OBJECTIVE: The importance of stress in the pathogenesis of essential hypertension is controversial. In this study we wanted to evaluate the relation between self-perceived stress and the blood pressure (BP) in a asymptomatic healthy population. SUBJECTS AND METHODS: A total of 1666 guests (mean +/- s.d. age 50 +/- 16 years) attending the air show AIR94 in Buochs, Switzerland volunteered to participate in a cross-sectional study. Using a self-administered questionnaire and visual analogue scales the individual stress perception and other cardiovascular risk behaviours/factors were assessed. BP, body weight, height, and the waist:hip ratio were measured. RESULTS: Individual stress perception was inversely related with the systolic BP (SBP) (r = -0.12, P < 0.001). The relationship was found in both men and women and was independent of age and/or body weight. No relation was found between the diastolic BP (DBP) and stress perception. Subjects with high normal BP according the JNC V classification showed a lower stress perception than did subjects with normal BP. In a multiple regression model the stress score was fourth most predictive of the SBP after body mass index, waist:hip ratio, and age followed by alcohol and fat intake. CONCLUSION: In this study we found an inverse association between the self-perceived stress and SBP. We suggest that the inverse association between BP and the self-perceived stress reflects a neuroendocrine and biochemical setting characterized by inadequate stress handling associated with a higher fat and alcohol intake and more abdominal fat tissue leading to a higher BP. Our data suggest that stress denial in combination with abdominal obesity, alcohol consumption, and smoking may be proxy for a high stress level.

Adult↗
PubMed1996

[Ambulatory therapy in varicose veins].

The treatment of varicose veins comprises conservative and active options. Every patient with varices has to be informed on the conservative modalities and should apply them in daily life. Compression therapy, as the most important part of the conservative treatment, should be considered individually for any patient according to the varicose-type, the grade of chronic venous insufficiency and the compliance of the patient. Active treatment modalities are clearly indicated in varices with complications such as trophic skin changes, varicophlebitis or when varices cause pain. But the cosmetic problem should not be underestimated. Morphologic and hemodynamic information obtained by noninvasive duplex technique allows the individualization of the surgical strategy for each patient. Besides surgical techniques used being less and less traumatic (invagination stripping, stab evulsion phlebectomy), more and more interventions are realized under ambulatory conditions in local anesthesia, even crossectomy with partial stripping of truncal varices. More important and complex operations, interventions involving more than one saphenous vein or reinterventions in recurrent varices are still performed under hospital conditions. They require only a short hospitalization time (2 to 4 days). Considering this very favourable evolution in surgery with a net trend to ambulatory, thus more economic treatment, the indications for sclerotherapy--a traditionally ambulatory modality with high recurrence-rate--are limited to reticular varices and telangiectasies.

Ambulatory Care↗
PubMed1995

Intravascular MR tracking catheter: preliminary experimental evaluation.

OBJECTIVE: This article reports on the preliminary evaluation of a new technique for guiding intravascular interventional procedures with MR imaging. Active real-time position monitoring of catheters with MR imaging is made possible by incorporating a small RF coil into the tip of the catheter. The purpose of this study was to evaluate the practicability and localizing precision of this MR catheter tracking technique in vitro and in vivo in comparison with fluoroscopy. MATERIALS AND METHODS: Feed cables employing a 0.9-mm-diameter coaxial cable, a 0.5-mm-diameter partially shielded coaxial cable, and a twisted pair cable attaching RF coils at the catheter tip to a coaxial plug at the catheter base were assessed. Further, miniature copper loop RF coils of two, three, and four turns were tested. In vitro validation of MR tracking was achieved by using a phantom consisting of a water-filled harvested segment of human aorta and iliac arteries embedded in gel. Accuracy of catheter placement was compared with MR and fluoroscopy. Subsequently, the MR tracking technique was evaluated in a swine model using a prototype 5-French MR tracking catheter. RESULTS: A fully shielded coaxial cable was found to be crucial for localizing the attached RF coil by means of the tracking technique. The number of coil turns had a lesser impact. Positions of the catheter tip measured with the MR technique and with fluoroscopy correlated well (r > .98), with a 6-mm 95% confidence interval of positional differences. Active real-time tracking of the coil-tipped catheters was achieved both in vitro and in vivo. The 5-French tracking catheter was successfully placed in the splenic and renal arteries of the swine. CONCLUSION: Robust in vivo tracking and accurate placement of catheters equipped with miniature RF coils are possible with MR imaging.

Animals↗
PubMed1989

The CaaX motif of lamin A functions in conjunction with the nuclear localization signal to target assembly to the nuclear envelope.

While the nuclear lamin proteins (A, B, and C) assemble specifically at the surface of the nuclear membrane, their sequences do not reveal stretches of hydrophobic amino acids that might explain their association with the nuclear membranes. However, the A and B lamin proteins possess Ras-like C-terminal CaaX sequence motifs, which in Ras proteins are sites of hydrophobic modifications required for membrane association and function. From the analysis of single and double lamin A mutants affecting the CaaX motif, the nuclear localization signal, and higher-order assembly properties, we propose that the CaaX motif functions as a nonspecific, low affinity membrane probe for proteins ultimately segregated to specific cellular membrane systems. Committed association with specific membranes requires additional interactions with membrane-resident factors.

Amino Acid Sequence↗
PubMed1983

Characterization of superoxide dismutase (SOD-1 and SOD-2) activities in inbred mice: evidence for quantitative variability and possible nonallelic SOD-1 polymorphism.

Liver Cu/Zn (SOD-1) and Mn (SOD-2) superoxide dismutase activities were determined in 12 inbred mouse lines. SOD-2 activity varied from 5 to 8 U/mg protein but was never more than 5% of the total. SOD-1 activity varied from 112 (SJL/J) to 155 (RF/J) U/mg protein, with the 12 strains falling into three activity classes. No correlation between SOD-1 activity and H-2 histocompatibility phenotype was observed, i.e., these two loci do not appear linked as previously suggested [Novak, R., Bosze, Z., Matkovics, B. and Fachet, J. (1980). Science 207:86]. Several tissues in all strains exhibited three SOD-1 charge electromorphs which did not differ in relative proportions between strains or tissues. The pI values of these three isozymes were 4.0, 4.5, and 5.0, respectively. The pI value of SOD-2 was 7.7. Both SOD-1 and SOD-2 were sensitive to CHCl3/EtOH extraction, but this sensitivity was not electromorph specific. Quantitation of the SOD-1 isozymic pattern indicated that the electromorphs were present at a ratio of 1:6:23 in order of increasing pI. Fitting of these data to a binomial distribution showed that they were consistent with the presence of two SOD-1 subunits (chains) of unequal pI. The mole fractions of the two chains were calculated to be 0.14 (lower-pI chain) and 0.86 (higher-pI chain). Since the mice used were highly inbred, this pattern could be due to unequal rates of transcription of linked, nonallelic SOD-1 loci, although other explanations are possible. The activity differences between SJL/J and RF/J appear large enough and the data precise enough to make genetic studies on the control of SOD-1 expression in the mouse practicable.

Animals↗
PubMedDate not supplied

Advances in vascular echoplanar imaging.

Magnetic resonance (MR) angiography is emerging as an increasingly useful tool for the noninvasive evaluation of the cardiovascular system. Ultrafast echoplanar imaging (EPI) data acquisition strategies are becoming more widely available. When applied to MR angiography, the associated reduction in data collection time allows breathheld acquisitions of entire vascular territories, as well as the exploitation of short-lived flow-enhancing measures. This paper describes technical aspects of EPI, its implementation into vascular imaging sequences, and associated artifacts. This is followed by a discussion of potential EPI MRA applications in the carotid and renal arteries, the portal venous system, and arteries and veins of the lower leg.

Arteries↗