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Biomedical subjects

C Meyer

Publications and source records attributed to C Meyer.

At least 55 records · Page 3Linked to original sources
PubMed2005

[3D motion adapted gating: a new navigator technique to shorten the acquisition time for coronary MRA].

PURPOSE: A major problem of free breathing coronary MR angiography (MRA) with respiratory navigator gating is low navigator efficiency and prolonged scan time due to irregular breathing patterns. 3D motion adapted gating (MAG) is a new adaptive navigator technique, which adapts in real time to changes of the end-expiratory position of diaphragm. This study evaluates the influence of 3D MAG on coronary MRA. METHODS AND MATERIALS: In 3D MAG, two additional gating windows are grouped around the conventional window. Additionally, each gating window is divided into three bands assigned to different portions of the k-space. The scan is terminated when three consecutive bands are filled and one complete image data set is collected. Free breathing navigator-gated coronary MRA was performed on 48 patients with suspected coronary artery disease. In random order, each patient underwent an ECG-gated, a 3D segmented k-space gradient echo sequence using 3D MAG and a conventional navigator technique. The coronary MRA was evaluated and compared using the following parameters: 1. navigator efficiency and scan time; 2. visualized coronary artery length; 3. qualitative assessment of image quality; and 4. detection of stenoses > 50 % in comparison with catheter angiography. RESULTS: Coronary MRA with 3D MAG had a significant increase in the average navigator efficiency (46 % +/- 12 % vs. 38 % +/- 12 %, p < 0.05), resulting in a significantly shorter scan time (mean: 18 % +/- 4 %, p < 0.05) for coronary MRA with 3D MAG compared to conventional navigator technique. Scans with and without 3D MAG had no significant differences in the continuously visualized vessel lengths, in the assessed image quality and in the sensitivity and specificity (83 % and 89 % vs. 83 % and 88 %, p > 0.05) of detecting coronary artery stenoses > 50 %. CONCLUSION: The 3D MAG technique improves the navigator efficiency and significantly (p < 0.05) shortens the scan time of navigator gated coronary MRA while maintaining image quality and diagnostic accuracy in the detection of coronary artery stenoses.

Adult↗
PubMed2005

[Magnetic resonance imaging of the brain in patients with cardiac pacemakers. Experimental and clinical investigations at 1.5 Tesla].

PURPOSE: In-vitro and In-vivo evaluation of feasibility and safety of MRI of the brain at 1.5 T in patients with implanted pacemakers (PM). MATERIALS AND METHODS: 24 PM models and 45 PM electrodes were tested In-vitro with respect to translational forces, heating of PM leads, behaviour of reed switch (activated vs. deactivated) and function at a 1.5 T MRI-system (actively shielded, maximum field gradient: 30 mT/m; rise time: 150 T/m/s). Based on these results, 63 MRI examinations in 45 patients with implanted PM were performed. Prior to MRI the PM were re-programmed in an asynchronous mode. The maximum SAR of MRI-sequences was limited to 1.2 W/kg. Continuous monitoring of ECG and pulse oximetry was performed during MRI. PM inquiry was performed prior to MRI, immediately after MRI and -- to assess long-term damages -- three months after the MRI exams, including determination of stimulation thresholds to assess potential thermal myocardial injuries at the lead tips. RESULTS: Translational forces (F (max) < or = 560 mN) and temperature increase (DeltaT (max) < or = 2.98 degrees C) were in a range which does not represent a safety concern from a biophysical point of view. No changes to the programmed parameters of the PM or damage of PM components were observed neither In-vitro (n = 0/24) nor In-vivo (n = 0/63). Despite the strong magnetic field, the reed switch remained deactivated in 54 % (13/24) of the cases during In-vitro simulated MRI exams of the brain. All patient studies (n = 63/63) could be completed without any complications. Atrial and ventricular stimulation thresholds (expressed as pulse duration at 2-fold rheobase) did not change significantly immediately post-MRI nor in the 3 months follow-up (pre-MRI: 0.17 ms +/- 0.13 ms, post-MRI: 0.18 ms +/- 0.14 ms, 3 months follow-up: 0.17 ms +/- 0.12 ms). CONCLUSION: MRI of the brain at 1.5 Tesla can be safely performed in carefully selected clinical circumstances when appropriate strategies are used (re-programming the PM to an asynchronous mode, continuous monitoring of ECG and pulse oximetry, limiting the SAR value of the MRI sequences, cardiological stand-by). Based on these studies, implanted PM should not longer be regarded as an absolute contraindication for MRI at 1.5 T.

Burns, Electric↗
PubMed2005

[Long-term fate of left atrial thrombi and incidence of cerebral embolism under continuous anticoagulation therapy].

PURPOSE: Patients (pts.) with atrial fibrillation (AF) and atrial thrombi are known to have an increased risk for cerebral embolism. However, little is known about the clinical course of atrial thrombi and the incidence of cerebral embolism in those patients during anticoagulation therapy. The high sensitivity of MR imaging (MRI) including diffusion-weighted imaging (DWI) suggests that this technique could provide an improved estimate of cerebral embolism associated with the presence of left atrial thrombi. The aims of this prospective study were to evaluate 1) the prevalence of clinically silent and apparent cerebral embolism in pts. with newly diagnosed AF and atrial thrombi using MRI/DWI, 2) the long-term fate of atrial thrombi under continues anticoagulation therapy and 3) the incidence of cerebral embolism during a follow-up period of 12 months with continuous anticoagulation therapy. MATERIALS AND METHODS: The study group consisted of 32 pts. with 1) newly diagnosed AF and evidence of left atrial (LA) thrombi detected by TEE and 2) a new start of anticoagulation therapy [International Normalized Ratio (INR) 2.0 - 3.0]. 19 pts. with 1) newly diagnosed AF and no evidence of atrial thrombi and 2) an equivalent anticoagulation regimen served as the control group. In both groups a) MRI/DWI studies of the brain (weeks 0, 4, 8, 12, 20, 28, 36, 44, and 52), b) transesophageal echocardiographic studies (TEE) for assessment of LA-Thrombi (weeks 0 and 52) and c) clinical neurological assessments (weeks 0, 20 and 52) were performed. RESULTS: In the study group (AF and LA-Thrombi) 11 out of 32 pts. (34 %) displayed signs of acute (n = 8) or chronic (n = 3) cerebral embolism in the initial MRI studies. In 4 out of 32 pts. (13 %), MRI/DWI depicted new or additional cerebral emboli (n = 12) during the follow-up period despite continuous anticoagulation therapy. 2 (n = 2/4; 50 %) of these patients had clinically apparent neurological deficits. In the control group 1 out of 19 pts. (5 %) showed evidence of chronic cerebral embolism as assessed by MRI/DWI at the beginning of the study (week 0). No embolic cerebral lesions were detected during the 12-month follow-up. Within 12 months only 63 % (n = 20/32) of LA thrombi in the study group resolved completely under anticoagulation. CONCLUSION: 1. The incidence of clinically inapparent cerebral emboli in pts. with newly diagnosed AF and atrial thrombi is much higher than the incidence of clinically apparent emboli and has been underestimated in the past. 2. New cerebral embolism may occur even with continued effective anticoagulation therapy in 13 % of pts. 3. Only 63 % of atrial thrombi resolve completely within 12 months under anticoagulation therapy.

Aged↗
PubMed2005

[The arteries of the humerus and their relevance in fracture treatment].

BACKGROUND: The purpose of the current work was to study the arterial blood supply of the humerus to evaluate impairments of the blood supply after humeral fractures and different methods of fracture treatment. METHODS: Arterial blood supply of the humerus was studied by corrosion injection technique in 6 cadaver preparations and is compared with the existing literature. RESULTS: Humeral head arteries originate from the circumflex humeral arteries. The major vessel enters the greater tubercle. Another group of vessels accesses the head from medially. The nutrient artery for the shaft enters into the medial third of the shaft. At the distal humerus there are multiple anastomoses with penetrating branches into both condyles and proximal to the radial, coronoid, and olecranon fossae. CONCLUSIONS: Fragments of a proximal humeral fracture usually have an independent blood supply. The medial vessels to the head gain high importance in fractures of the anatomical neck. The nutrient artery lies regularly medial to the humeral mid-shaft and is at risk at open reduction of this region. The abundant vessels at the entire distal humerus ensure sufficient vascularization of the fragments after fracture.

Arteries↗
PubMed2005

No considerable long-term weight gain after smoking cessation: evidence from a prospective study.

The aim of the study was to analyse predictors of the body mass index (BMI) after smoking cessation. The sample included 4075 residents aged 18-64 years in a northern German area (participation rate 70.2%), drawn randomly from the resident registration files, among them 1545 current and 903 former daily smokers. The current smokers were followed up 36 months after baseline. Face-to-face in-home computer-aided interviews (Composite International Diagnostic Interview) including questions about body weight and height at baseline and postal questionnaires at follow-up were employed. The data reveal that the number of cigarettes smoked at time of peak consumption in life contributed substantially, and years of abstinence from daily smoking contributed marginally to the BMI in a general linear model. It is concluded that the contribution of smoking cessation to the BMI increase was practically negligible. Efforts to prevent weight gain after smoking cessation should focus especially on heavy smoking.

Adolescent↗
PubMed2005

Influence of psychiatric comorbidity in alcohol-dependent subjects in a representative population survey on treatment utilization and natural recovery.

BACKGROUND: It is well known that only a minority of alcohol-dependent subjects seek help and that the majority of alcohol-dependent individuals recover without utilization of formal help. Psychiatric comorbidity is highly prevalent among alcohol-dependent individuals. However, no data are available on the impact of psychiatric comorbidity on natural recovery. AIMS: To analyse the impact of non-psychotic psychiatric comorbid Axis I disorders on remission rate and utilization of formal help in alcohol-dependent individuals drawn from a representative general population sample in northern Germany (response rate: 70.2%, n = 4075). Psychiatric diagnoses and utilization of help were assessed in a personal interview using standardized instruments. One hundred and fifty-three life-time alcohol-dependent individuals were assessed, among whom 98 fulfilled the criteria for sustained long-term remission according to the Diagnostic and Statistical Manual version II (DSM-IV) criteria. Any coincidence of DSM-IV non-psychotic Axis I disorders with alcohol dependence was counted as comorbidity. Comorbidity rate in the whole sample was 36.1%. RESULTS: The rate of individuals who remitted from alcohol dependence without formal help was 36.9% in the non-comorbid and 42.6% in the comorbid group. Utilization of formal help was unrelated to comorbidity. Dually diagnosed subjects without a history of help-seeking showed minor differences concerning reasons for not seeking help. Seeking help was not related to schooling, severity of dependence and gender. CONCLUSION: Data reveal that remission without formal help is equally prevalent among non-comorbid as among comorbid alcohol-dependent individuals. Axis I comorbidity is not related directly to utilization of alcohol-related help. Negative prognoses for untreated comorbid alcohol-dependent individuals are not justified from an epidemiological point of view.

Adolescent↗
PubMed2005

Nitrate, a signal relieving seed dormancy in Arabidopsis.

Nitrate is an important nitrogen source for plants, but also a signal molecule that controls various aspects of plant development. In the present study the role of nitrate on seed dormancy in Arabidopsis was investigated. The effects of either mutations affecting the Arabidopsis nitrate reductase genes or of different nitrate regimes of mother plants on the dormancy of the seeds produced were analysed. Altogether, data show that conditions favouring nitrate accumulation in mother plants and in seeds lead to a lower dormancy of seeds with little other morphological or biochemical differences. Analysis of germination during seed development indicated that nitrate does not prevent the onset of dormancy but rather its maintenance. The effect of an exogenous supply of nitrate on seed germination was tested: nitrate in contrast to glutamine or potassium chloride clearly stimulated the germination of dormant seeds. Data show, moreover, that the Arabidopsis dual affinity nitrate transporter NRT1.1 (CHL1) may be involved in conveying the nitrate signal into seeds. Thus, nitrate provided exogenously or by mother plants to the produced seeds, acts as a signal molecule favouring germination in Arabidopsis. This signalling may involve interaction with the abscisic acid or gibberellin pathway.

Abscisic Acid↗
PubMed2005

Increased renal glucose metabolism in Type 1 diabetes mellitus.

AIMS: In poorly controlled diabetes, increased renal glucose uptake has been implicated in the pathogenesis of diabetic nephropathy by promoting nonenzymatic glycosylation of proteins, activation of protein kinase C, and increased polyol pathway flux. However, whether glucose uptake by the diabetic kidney is actually increased, especially in patients with Type 1 diabetes, is unclear. METHODS: To examine this question, we used a combination of net balance and isotopic techniques to compare renal glucose uptake in 12 subjects with Type 1 diabetes before and after restoration of near normoglycaemia by infusion of insulin with that in 15 postabsorptive nondiabetic volunteers. RESULTS: Prior to insulin infusion, the diabetic subjects were markedly hyperglycaemic (arterial glucose 15.8 +/- 0.9 vs. 4.4 +/- 0.1 mm) and their renal tissue glucose uptake (i.e. total glucose disappearance across the kidney minus glycosuria) was increased more than 2 1/2-fold (388 +/- 43 vs. 148 +/- 12 micromol/min, P < 0.001). This was wholly explained by the mass action effects of hyperglycaemia since the diabetic subjects had normal renal blood flow (1575 +/- 82 vs. 1492 +/- 68 mL/min, P = 0.46) and reduced renal tissue glucose fractional extraction (1.7 +/- 0.2 vs. 2.3 +/- 0.1%, P = 0.027). Insulin infusion for three hours, which restored near normoglycaemia (arterial glucose 7.6 +/- 0.7 mm), reduced renal tissue glucose uptake toward normal (258 +/- 41 micromol/min, P = 0.006) without altering renal blood flow (1557 +/- 110, P = 0.63) or renal tissue glucose fractional extraction (2.1 +/- 0.3%, P = 0.35). Renal and hepatic glucose release, which had been increased (419 +/- 49 and 960 +/- 54 vs. 204 +/- 9 and 734 +/- 32 micromol/min, both P < 0.001), were suppressed by insulin to 138 +/- 22 and 520 +/- 53 micromol/min, respectively (both P < 0.001). CONCLUSIONS: In poorly controlled Type 1 diabetes, renal glucose uptake is markedly increased, which provides a link between hyperglycaemia and biochemical processes implicated in the pathogenesis of diabetic nephropathy. Its reversal by restoration of near normoglycaemia with insulin may explain the benefit of intensive insulin therapy in preventing diabetic nephropathy.

Adult↗
PubMed2005

[Micro-CT analysis of cancellous bone fragments from the distal radius fracture zone in osteoporosis].

The incidence and prevalence of osteoporosis must be considered to continue to increase significantly due to the expected demographic development and environmental changes. In the diagnosis and staging of osteoporosis the three-dimensional bone structure should be as important as the bone mass or the mineral content of the bone. In this study, microfragments were taken from distal radius fracture zones and investigated in Micro-CT scans. Patients in which osteodensitometry of the lumbal spine had revealed osteoporosis in were found to have significantly reduced bone mass, bone density and trabecular thickness. Trabecular fractures which were found in non-osteoporotic patients even in robust trabeculae were detected by the two-dimensional analysis in thin locations and arborizations. Despite some trabeculae turned out to be very small the differences in the histomorphometry and the quality of trabecular fractures in osteoporotic as well as non-osteoporotic patients could be visualized very good in the Micro-CT analysis.

Absorptiometry, Photon↗
PubMed2005

Insulin-sensitisers in the treatment of polycystic ovary syndrome.

Polycystic ovary syndrome (PCOS) is a common endocrine condition with reproductive and metabolic implications. In the current setting there is an evolving, yet inadequate, understanding of the pathophysiology, long-term health implications and ideal therapies for women with PCOS. Insulin resistance, secondary to both genetic and lifestyle factors, is integrally involved in the pathogenesis, the metabolic and clinical features and the long-term sequelae of PCOS in a majority of patients. Therapeutic strategies targeting insulin resistance ameliorate clinical features and may reduce long-term sequelae of PCOS, including diabetes. The main benefit of improved insulin resistance is to improve fertility and potentially to improve clinical features of hyperandrogenism and lower androgen levels. Insulin sensitisers also have the potential to delay the development of diabetes and cardiovascular disease in PCOS. Lifestyle therapy is indicated as the first intervention; however, metformin as an insulin sensitising agent has a role in first-line medical therapy in women with PCOS. Further research is needed to define the role of insulin sensitisers in PCOS and to determine the long-term risks and benefits of these therapies.

Body Weight↗
PubMed2005

Clinical and clinicopathological changes in 6 healthy ponies following intramuscular administration of multiple doses of imidocarb dipropionate.

Haematological variables and selected serum indices, particularly those affected by changes in renal and hepatic function, were examined in 6 healthy ponies following 4 intramuscular doses of 4 mg/kg imidocarb dipropionate administered every 72 hours. This treatment regime has been reported to sterilise experimental Babesia equi infections in horses and may have value in preventing the spread of this disease during exportation of possible carrier horses to non-endemic countries. Serum bile acids and serum gamma glutamyltransferase activity were measured to evaluate the effect of this treatment regime on hepatic function. Owing to the absence of any increase in these variables it was concluded that this treatment regime had no clinically detectable deleterious effect on hepatic function in healthy ponies. Urinary gamma glutamyltransferase : creatinine ratios (IU/g), serum creatinine and fractional clearance of sodium, potassium and phosphate (%) were calculated as a measure of renal function. Urinary GGT and urinary GGT : creatinine ratios were significantly elevated on Day 5 of the trial, with 2 of the trial animals also exhibiting mild azotaemia indicative of changes in renal function. The changes in urine GGT : urine creatinine ratios observed in this study also provides evidence of the value of this ratio for the early detection of renal toxicity, following exposure to nephrotoxic agents.

Animals↗
PubMed2004

Advantages and disadvantages of different nasal CPAP systems in newborns.

OBJECTIVE: To compare three different systems of continuous positive airway pressure (CPAP): the naso-pharyngeal tube and two-prong systems in newborns, focusing on duration of CPAP, side effects and cost. DESIGN: Randomized clinical study. PATIENTS: Between July 2000 and September 2001 newborns were randomized to three different CPAP systems. Forty infants in two weight groups (>2500 g and 1250-2500 g; 20 patients in each group) were included. RESULTS: In the group >2500 g the median duration of CPAP was 1.1 days (range 0.25-14.3 days). The median time on a naso-pharyngeal CPAP was 1 day (range 0.25-14.3 days), on Hudson prongs 1.6 days (range 0.5-3.3 days) and on the Infant Flow system 0.7 days (range 0.3-13.6 days; p>0.05 for comparison between groups, Fisher's exact test). With naso-pharyngeal CPAP, 2 patients developed moderate nasal injuries. On Hudson, 2 patients developed moderate and three mild nasal injuries. One patient on the Infant Flow showed mild and one moderate nasal injuries. In the weight group 1250-2500 g the median duration of CPAP was 1.1 days (range 0.1-7.0 days). The median time on the naso-pharyngeal tube was 0.9 days (range 0.1-7 days), on Hudson prongs 1.1 days (range 0.7-6.6 days) and on the Infant Flow system 1.3 days (range 0.25-5.9 days; p>0.05 for comparison between groups, Fisher's exact test). With a naso-pharyngeal tube, one infant developed mild and one moderate nasal injuries. On Hudson prongs, two had moderate nasal injuries. On Infant Flow, one newborn showed a severe nasal injury and two mild injuries. None of the patients developed a pneumothorax. CONCLUSION: The naso-pharyngeal tube is an easy, safe and economical CPAP system usable with every common ventilator. For very low birth weight newborns, a prong system may have advantages.

Birth Weight↗
PubMed2004

Plant growth and the TOR pathway.

In mammalian, insect, and yeast cells, TOR proteins are essential regulators of cell growth in response to environmental signals including nutrients, mitogens, and stresses. Although many aspects of the TOR-dependent signalling pathway are conserved between animals and fungi, important differences have also been found and are likely to be related to the ecophysiological adaptations of these organisms. The TOR protein also exists in plants. This review will first discuss specific aspects of plants concerning the contribution of cell growth to overall growth, as well as their responses to nutrient starvation, with emphasis on recent results obtained through genetic analysis in the model plant Arabidopsis thaliana. This is followed by the current status of the genetic analysis of the TOR gene in this plant and the search for potential members of a TOR pathway in the Arabidopsis genome.

Arabidopsis↗
PubMed2004

[Adverse events following immunisation in Germany from 1.1.2001 to 31.12.2003].

The German Protection Act against Infection (Infektionsschutzgesetz) came into effect on 1 January 2001. Physicians must report complications after vaccination to local heath authorities according to Article 6 No. 3. . The local heath authorities send notifications to the Paul-Ehrlich-Institut (PEI). Between 1 January 2001 and 31 December 2003, a total of 941 reports from local public health authorities were registered in a central database and assessed. Compared to the number of reports of suspected adverse drug reactions sent to the PEI independently in the same time period by the pharmaceutical companies and the German Drug Commissions (Arzneimittelkommissionen) (n=2.338), underreporting has to be considered. Age distribution in the reports from local public health authorities revealed the following pattern: 33.8% of reports concerned adults (18-59 years old), 25.4% children aged 1-6 years, 16.9% infants, 11.3% adults (>60 years), 8.9% children aged 7-14 years and 1.9% adolescents aged 15-17 years. In 1.8% the age was not reported. The causal relationship was assessed by the PEI as proven in 0.2%, probable in 41.6%, likely in 27.5% and unlikely in 6.6%. In 11.9% assessment was not possible and in 11.8% of the reports follow-up information has been requested. Comparison to the reports from other sources revealed no major difference in respect to quality and content.

Adolescent↗
PubMed2004

[Vaccine opponents and sceptics. History, background, arguments, interaction].

Scepticism and critical attitudes towards immunisation have prevailed since the introduction of the smallpox vaccine. In Germany the anti-vaccine movement is rather small (3-5% of the population). Nevertheless its influence on the acceptance of immunisation by the population may be substantial, as shown by the examples of smallpox vaccination and the recent discussion of the combined MMR vaccine in the UK. Modern societies facilitate networking and the dissemination of anti-vaccination ideas. The decline in the incidence of vaccine-preventable diseases has led to a reduced awareness of possible complications from infectious diseases and to an overestimation of the incidence of rarely occurring adverse events following immunisation. Proposals for managing the anti-vaccine movement must take into account changes in immunisation policies and draw on elements of risk communication.

Adult↗
PubMed2004

[Difficulties involved in the Hoffa fractures].

To study the outcome in Hoffa fractures regarding the type of fracture, concomitant injuries, and different treatments. From January 1996 until December 2002, 7 Hoffa fractures (6 patients) from a total of 79 distal femoral fractures were treated in the Department of Trauma Surgery, University Hospital of Giessen. The results were evaluated by Neer's score. For the evaluation of postoperative vascularization of the distal femur, clinical and radiological findings were compared with anatomical studies of the bone arteries by corrosion preparations. Fracture consolidation was seen in all cases. Patients with an isolated Hoffa fracture achieved a score of 89.0 (82-97) according to Neer. One patient suffering initially from nonunion achieved 68 points after bone union. One polytraumatized patient with bilateral Hoffa fracture achieved a satisfying result (score value of 72) and a bad result (score value of 38). Multiple small nutrient arteries of the distal femur originate from the "rete articulare genus." They can be expected to ensure the arterial blood supply. Hoffa fracture is a very rare injury. In our patients, careful surgical treatment with open reduction and safe screw fixation yielded good to very good results.

Adult↗
PubMed2004

Self-efficacy to refrain from smoking predicted by major depression and nicotine dependence.

Little is known about the specific pathways between depression and low self-efficacy to stop smoking, particularly among the general population. The goal was to examine whether depression and nicotine dependence may predict the confidence in the ability to refrain from smoking (CAS). A random population sample aged 18-64 was used from northern Germany. It included 1520 current smokers, who were eligible for a first follow-up after 30 months and a second follow-up after 36 months. The results show that DSM-IV major depression and nicotine dependence, the Fagerström Test for Nicotine Dependence (FTND), the number of cigarettes smoked, the age at onset of daily smoking, and the intention to stop smoking predict the CAS. It is concluded that there may be an additive effect from nicotine dependence and major depression on the CAS.

Adolescent↗