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Biomedical subjects

C Weiss

Publications and source records attributed to C Weiss.

At least 37 records · Page 2Linked to original sources
PubMed2004

[Normoxia ?].

Under the aspect of tissue O (2)-supply anatomical and functional features within the range of the microcirculation are described. With regard to "Normoxia?" the term "critical pO (2)" is introduced, its functional role discussed and data from earlier studies are presented. Recent investigations on the dependence of the accumulation of HIF's (Hypoxia inducible factors) which increase tissue O (2)-supply and lower O (2)-demand, have shown that HIF-accumulation increases steeply below a tissue pO (2) of 20 mm Hg, thus in a pO (2) range where earlier investigators determined their pO (2)(crit.) data. Apparently, the the pO (2)(crit.) of a tissue marks the boundary between Hypoxia and Normoxia. Under normoxic conditions O (2)-consumption is limited by tissue O (2)-demand, under hypoxic conditions consumption is limited by O (2)-supply.

Humans↗
PubMed2004

[Twist-guided thread control: a technique for faster and atraumatic continuous sutures].

A simple technique by twisting the thread in clockwise or counter clockwise direction before tightening the suture can help to produce a regular vascular suture line. In a blinded experiment with 60 vascular anastomosis it was proved that the time needed for suture can be reduced by 15%, and that traumatic touch with surgical instruments can be diminished by 63%.

Anastomosis, Surgical↗
PubMed2004

The caries-preventive potential of subablative Er:YAG and Er:YSGG laser radiation in an intraoral model: a pilot study.

OBJECTIVE: The aim of the present study was to investigate the effect of sub-ablative Er:YAG and Er:YSGG laser radiation on the demineralization of human dental enamel in situ. METHODS: Eighteen enamel specimens were prepared to this end, nine of which were irradiated at 8 J/cm(2) with the Er:YSGG laser and nine at 6 J/cm(2) with the Er:YAG laser (125 pulses per surface). Each test surface was assigned a control surface on the same specimen. Three healthy volunteers from each group subsequently wore three enamel specimens in situ for a period of 1 week. The demineralization was assessed by determining the surface microhardness according to Knoop (KH) before and after wearing. RESULTS: Before wearing, the mean surface hardness measured on the control surfaces was 233 (SD 99) KH (CYSGG) and 162 (SD 59) KH (CYAG). After sub-ablative laser irradiation, the surface hardness values measured were already found to be lower compared to the untreated control surfaces (YSGG: 195 [SD 110] KH/YAG: 112 [SD 72] KH). Marked demineralization was observed on the control surfaces after 1 week of wearing in situ (CYSGG*: 60 [SD 57] KH; CYAG*: 53 [SD 9] KH). After wearing, the hardness on the irradiated test surfaces was ErYSGG*: 133 [SD 58] KH and ErYAG*: 89 [SD 28] KH, and was thus higher than on the control surfaces. CONCLUSIONS: The results indicate a tendency towards increased caries resistance following sub-ablative erbium laser irradiation. However, in an analysis of variance model with repeated measures, the tendency in this study failed to reach statistical significance (alpha = 0.05).

Dental Caries↗
PubMed2004

Exercise-induced activation of coagulation in subjects with activated protein C resistance.

In the healthy individual intensive physical exercise leads to a minor activation of blood coagulation that appears to be balanced by a concomitant activation of the fibrinolytic system. This study tested the hypothesis that vigorous exercise might give rise to an exaggerated activation of coagulation in subjects with resistance to activated protein C (APC). Molecular markers of thrombin (prothrombin fragment 1 + 2, thrombin-antithrombin III complexes) and fibrin formation (fibrinopeptide A), as well as markers of the fibrinolytic activity (plasmin-antiplasmin complexes, D-dimers), were determined in nine asymptomatic male individuals with APC resistance [age, 18 +/- 3 years; maximal oxygen consumption, 56.7 +/- 2.7 ml/kg per min (mean +/- standard deviation)] and in nine male control subjects (age, 19 +/- 4 years; maximal oxygen consumption, 56.2 +/- 3.2 ml/kg per min) after 1 h of running to exhaustion. Baseline levels of prothrombin fragment 1 + 2 were higher in individuals with APC resistance than in controls [0.67 +/- 0.06 nmol/l (mean +/- standard error) versus 0.48 +/- 0.01 nmol/l; P < 0.05]. In response to exercise, hemostatic variables significantly increased in both groups to a similar small extent. Likewise, exercise-induced changes of fibrinolytic variables in subjects with APC resistance paralleled those observed in controls. In summary, exhaustive running in subjects with APC resistance does not provoke an abnormal hemostatic or fibrinolytic response, suggesting that vigorous exercise does not imply an increased risk for thrombosis in young male subjects with APC resistance.

Activated Protein C Resistance↗
PubMed2003

Exclusive annihilation pp-->gammagamma in a generalized Parton picture.

Exclusive proton-antiproton annihilation into two photons at large s ( approximately 10 GeV2) and /t/,/u/ approximately s can be described by a generalized parton picture analogous to the "soft mechanism" in wide-angle real Compton scattering. The two photons are emitted in the annihilation of a single fast quark and antiquark. The matrix element describing the transition of the pp system to a qq pair can be related to the timelike proton elastic form factors as well as to the quark/antiquark distributions measured in inclusive deep-inelastic scattering. The reaction could be studied with the proposed 1.5-15 GeV high-luminosity antiproton storage ring (HESR) at GSI.

Journal Article↗
PubMed2003

Development of PCR-based markers linked to dominant genes for male-fertility restoration in Pampa CMS of rye (Secale cereale L.).

Cytoplasmatic male sterility (CMS) is the basis for commercial hybrid seed production of rye. Nuclear restorer genes are indispensable for a complete restoration of fertility of the CMS lines. The drawbacks of current European restorer lines require the utilisation of new genetic resources that have been recently detected in an Iranian primitive rye population (IRAN IX) and an Argentinean landrace (Pico Gentario). The introgression of these effective restorer genes (Rfp1 and Rfp2, respectively) into breeding material can be facilitated by marker-assisted selection. Using two F(2) populations based on crosses between the non-restorer inbred line Lo6 and the restorer IRAN IX, as well as Pico Gentario, RAPDs and AFLPs were screened and led to a closely linked marker set for each of these genes. The conversion of the closest markers into fragment-specific sequence-characterised amplified region (SCAR) markers resulted in flanking ranges of 2.9 cM (Rfp1) and 5.2 cM (Rfp2). The application of these markers in backcross programmes is discussed.

Genes, Dominant↗
PubMed2003

Reproducibility of a four-point clinical severity score for glabellar frown lines.

BACKGROUND: Focal injections of botulinum toxin A are used successfully for the treatment of hyperkinetic facial wrinkles. Efficacy can be measured by several methods. However, so far none has been investigated for its reproducibility. Objectives To investigate the reproducibility of a clinical 0-3 score for glabellar frown lines. METHODS: In the first part of the study, a standardized photographic documentation of glabellar frown lines was produced. Based on the results of this phase, a consensus atlas of glabellar frown lines was developed and participants were trained using this atlas. In the main study, 50 standardized photographs were shown on two consecutive days to 28 dermatologists. The reproducibility of the score was investigated by conventional kappa statistics. RESULTS: In the main study, we found an unweighted kappa according to Fleiss of 0.62 for interobserver reproducibility. Intraobserver reproducibility showed an unweighted kappa according to Cohen of between 0.57 and 0.91 for each observer, and a weighted kappa according to Cicchetti and Allison of between 0.68 and 0.94. CONCLUSIONS: The clinical 0-3 score for glabellar frown lines shows a good inter- and intraobserver reproducibility.

Female↗
PubMed2002

Impaired eyeblink conditioning and decreased hippocampal volume in PDAPP V717F mice.

We examined heterozygous transgenic (Tg) mice that overexpress V717F amyloid precursor protein (APP) for delay eyeblink conditioning (EBC) and hippocampal volume with magnetic resonance imaging (MRI). Platelet-derived APP mice were significantly impaired on EBC relative to wild type (WT) litter-mate controls. T2-weighted spin echo images (62.5 x 125 x 500 microm) of the same mice were acquired under anesthesia using a 9.4T magnet. Tg mice had hippocampal to brain volume ratios that were significantly smaller than WT controls (31% smaller in the rostral dorsal hippocampus, 13-22% smaller among equal dorsal-ventral thirds of a caudal section). These results indicate that overexpression of APP or beta amyloid profoundly affects learning and memory and hippocampal volume. The results also indicate that eyeblink conditioning and quantitative MRI in mice may be useful assays to follow the progression of disease-related changes, and to test the effectiveness of potential therapeutics against Alzheimer's disease.

Alzheimer Disease↗
PubMed2002

[Ultrasound examination technique of the elbow and wrist joints].

Ultrasound examination of the elbow and hand is invaluable in diagnostics of acute and chronic joint diseases. Ultrasound is a noninvasive, immediately available procedure without radiation, which should be performed after exploration and clinical examination. It cannot, however, replace radiographic examination because the cortical substance represents a barrier for the ultrasound waves so that bony lesions (i.e., intraosseous tumors or osteomyelitis) cannot be detected. In the diagnosis of periarticular soft tissue lesions and intra-articular changes (loose bodies, intra-articular effusion, or synovitis), ultrasound represents an excellent cost-effective method supplying additional information. The sonographic technique is presented with the standard sectional planes according to the directives given by the working group on the musculoskeletal system of the German Society for Ultrasound in Medicine (DEGUM) issued on 20 January 1996.

Cost-Benefit Analysis↗
PubMed2002

[Ultrasound diagnosis of the elbow joint in fracture of the head of the radius].

Imaging guidelines have been proposed by the German Society of Ultrasonography (DEGUM, 1996) for the locomotor apparatus using five standardized sections of the elbow that allow a reproducible presentation of the surrounding soft tissues and cortical landmarks of this joint. Intra-articular fractures form a variable amount of hematoma, which is easily detected by ultrasound using the proposed standardized sectional planes. Ultrasonography is a cost-effective, easy-to-use and radiation-free method to exclude intra-articular fractures of the elbow. Intra-articular effusions and effusions besides the radial head are indirect signs of bony involvement. Suspected radial head injuries in children and adults can easily be examined by ultrasound. Detection of intra-articular effusions may then lead to further investigation with magnetic resonance imaging (MRI) when needed. MRI is unnecessary when ultrasonography shows no effusions in elbow injuries.

Adult↗
PubMed2002

[Ultrasound imaging of the patellar gliding groove].

Ultrasound is a noninvasive, immediately available procedure without radiation, which should be performed after exploration and clinical examination. It cannot, however, replace radiographic examination because the cortical substance represents a barrier for the ultrasound waves so that bony lesions (i.e., intraosseous tumors or osteomyelitis) cannot be detected. In the diagnosis of periarticular soft tissue lesions and intra-articular changes, i.e., loose bodies, intra-articular effusion, or synovitis, ultrasound represents an excellent cost-effective method supplying additional information and should be performed before using more costly techniques (magnetic resonance imaging). Ultrasound of the femoral patellar groove is limited because of the higher location of the patella. The area of the dorsal patella is not approachable for ultrasound. The sonographic technique is presented with standard sectional planes according to the directives given by the working group on the musculoskeletal system of the German Society for Ultrasound in Medicine (DEGUM) issued on 20 January 1996.

Humans↗
PubMed2002

Therapeutic outcome and side-effects after radiotherapy, chemotherapy and/or hyperthermia treatment of head and neck tumour xenografts.

The aim of the study was to optimise the still unsatisfactory therapeutic results in head and neck cancer by studying the results and the side-effects of radiotherapy, chemotherapy and/or local hyperthermia treatment of human tumour xenografts. Mice carrying human-derived head and neck squamous cell carcinoma xenografts with a mean volume of 100 mm(3) received 5x2 Gy, cisplatin or ifosfamide and/or local hyperthermia at 41/41.8 degrees C. Haematocrit and tumour volumes were determined two or three times per week, respectively, until day 25 or day 60. At day 60, the highest number of complete remissions (CRs) (80%) was observed in the triple modality therapy group with radiation, local hyperthermia at 41.8 C and cisplatin at a dosage of 2 mg/kg body weight (b.w.). Therapeutic side-effects were moderate weight loss and a mild anaemia. Thus, with regard to the long-term tumour-free survival, the most effective treatment was the combination of radiotherapy, cisplatin and local hyperthermia at 41.8 C.

Animals↗
PubMed2002

Endothelial function in patients with peripheral vascular disease: influence of prostaglandin E1.

Peripheral arterial occlusive disease (PAOD) is characterized by atherosclerotic lesions in large vessels and disturbances on the microcirculatory level. In the local regulation of vascular tone and microvascular perfusion, vascular endothelium plays a key role. For many years prostaglandin E1 (PGE1) has been used for the treatment of PAOD. Because PGE1 has only moderate effects on blood flow other mechanisms may be relevant for the therapeutical efficacy. The aim of our pilot study was to evaluate endothelial function in patients with PAOD and to investigate the impact of PGE1 on endothelial-dependent vasodilation in peripheral vesselsIn 8 controls and in 8 patients with PAOD stage II, endothelial-dependent vascular responses of the femoral vessels to increasing doses of acetylcholine (30,60,90 microg/min) were determined by Doppler flow velocity measurements in the common femoral artery. Furthermore, vascular reactivity was evaluated before and immediately after intravenous infusion of 30 microg PGE1/30 min in patients. Endothelial-dependent vasodilation was significantly reduced in patients with PAOD compared to control subjects. Infusion of PGE1 neither increased blood flow in the common femoral artery nor endothelium-dependent vasodilation of peripheral resistance vessels as indicated by unchanged reaction to acetylcholine. In conclusion, endothelial function is impaired in patients with PAOD. Administration of PGE1 did not increase femoral artery blood flow or improve endothelial-dependent reactivity of peripheral resistance vessels in patients with PAOD. Therefore, beneficial effects of PGE1 in peripheral vascular disease cannot be attributed to an increase in blood supply or an improvement of endothelial-dependent vasodilation.

Aged↗
PubMed2002

T cell reactivity against the SmD1(83-119) C terminal peptide in patients with systemic lupus erythematosus.

BACKGROUND: The SmD1(83-119) peptide is a major target of the B cell response in patients with systemic lupus erythematosus (SLE). OBJECTIVE: To investigate the T cell response directed against this peptide, its disease specificity, and possible impact on SLE pathogenesis. METHODS: Peripheral blood mononuclear cells derived from 28 patients with SLE and 29 healthy and disease controls were stimulated by the SmD1(83-119) and the recombinant (r)SmD1 protein, and [3H]thymidine incorporation was measured. Patients with SLE were simultaneously tested for autoantibodies, disease activity, clinical symptoms, and medical treatments. RESULTS: T cell reactivity against the SmD1(83-119) peptide was detected in 11/28 (39%) patients with SLE and against the rSmD1 protein in 10/28 (36%) patients. In contrast, only 2/29 (7%) controls exhibited SmD1 reactivity. An analysis of proliferation kinetics showed that SmD1 reactive T cells are activated in vivo, as additionally confirmed by cytometric analysis. Addition of mammalian dsDNA to rSmD1 enhanced the rSmD1-specific T cell response. SmD1(83-119)-specific T cell reactivity was significantly more common in patients with cardiac and pulmonary symptoms. No correlation between T and B cell responses and disease activity was seen. CONCLUSION: SmD1(83-119) is a major T cell epitope of SmD1, commonly recognised by T cells from patients with SLE and much less commonly found by healthy or disease controls. This strong T cell reactivity as well as the high frequency and specificity of anti-SmD1(83-119) antibodies in SLE suggest a possible role in SLE pathogenesis, at least in a subset of patients.

Adult↗
PubMed2002

Electromyography as a recording system for eyeblink conditioning with functional magnetic resonance imaging.

This study was designed to develop a suitable method of recording eyeblink responses while conducting functional magnetic resonance imaging (fMRI). Given the complexity of this behavioral setup outside of the magnet, this study sought to adapt and further optimize an approach to eyeblink conditioning that would be suitable for conducting event-related fMRI experiments. This method involved the acquisition of electromyographic (EMG) signals from the orbicularis oculi of the right eye, which were subsequently amplified and converted into an optical signal outside of the head coil. This optical signal was converted back into an electrical signal once outside the magnet room. Electromyography (EMG)-detected eyeblinks were used to measure responses in a delay eyeblink conditioning paradigm. Our results indicate that: (1) electromyography is a sensitive method for the detection of eyeblinks during fMRI; (2) minimal interactions or artifacts of the EMG signal were created from the magnetic resonance pulse sequence; and (3) no electromyography-related artifacts were detected in the magnetic resonance images. Furthermore, an analysis of the functional data showed areas of activation that have previously been shown in positron emission tomography studies of human eyeblink conditioning. Our results support the strength of this behavioral setup as a suitable method to be used in association with fMRI.

Acoustic Stimulation↗
PubMed2001

Nanomechanical resonator shuttling single electrons at radio frequencies.

We observe transport of electrons through a metallic island on the tip of a nanomechanical pendulum. The resulting tunneling current shows distinct features corresponding to the discrete mechanical eigenfrequencies of the pendulum. We report on measurements covering the temperature range from 300 down to 4.2 K. We explain the I-V curve, which unexpectedly differs from previous theoretical predictions, with model calculations based on a master equation approach.

Journal Article↗