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Biomedical subjects

Martin Weber

Publications and source records attributed to Martin Weber.

At least 19 recordsLinked to original sources
PubMed2006

Treating auditory hallucinations by transcranial magnetic stimulation: a randomized controlled cross-over trial.

BACKGROUND: In a previous functional magnetic resonance imaging study, the authors succeeded in demonstrating the activation of Heschl's gyrus during auditory hallucinations (AH). OBJECTIVES: This study aims to treat AH specifically by repetitive transcranial magnetic stimulation (rTMS). METHODS: 16 patients with AH were included in a randomized, cross-over, sham-controlled trial. 1 Hz rTMS was administered over the left and right temporo-parietal cortex and sham position, respectively, on 5 consecutive days; 900 stimuli each, strength 100% of motor threshold. Using the Psychotic Symptom Rating Scales (PSYRATS), the hallucinations during the stimulation periods and 4-week follow-ups were quantified. Electroencephalograms (EEG) were acquired before and after each period. RESULTS: Treatment responses were observed after left hemisphere rTMS only. The 5 patients who showed a response did so already after 2 days. However, group mean hallucination scores did not differ across treatment conditions. No significant changes were found in EEG after rTMS. CONCLUSIONS: A subgroup of patients suffering from AH benefits soon after treatment start from rTMS over the left superior temporal gyrus as revealed by the decrease of AH scores compared to right-sided and sham procedures.

Analysis of Variance↗
PubMed2005

[The transfibular approach for ankle arthrodesis].

OBJECTIVE: Bony fusion between tibia and talus in neutral position of foot. Return to a pain-free function of the lower limb. INDICATIONS: Extensive loss of articular cartilage accompanied by a painful and considerably limited motion with or without malalignment. Partial avascular necrosis of talar dome or distal tibial epiphysis. Neuroarthropathy (Charcot joint) with progressive malalignment of ankle. Revision surgery after failed total ankle arthroplasty. CONTRAINDICATIONS: Acute purulent joint infection. Total avascular necrosis of talus. SURGICAL TECHNIQUE: Posterolateral approach to the distal fibula taking care to preserve the periosteal vessels. Fibular osteotomy from proximal lateral to distal medial. Division of the anterior tibiofibular, anterior fibulotibial, and fibulocalcaneal ligaments. Division of posterior tibiofibular ligament. Transverse planar resection of tibial and talar articular surfaces. Freshening of the medial malleolus. Resection of the tip of medial malleolus through a medial incision. Positioning of talus perpendicular to the tibia, paying attention to the valgus of the hindfoot and external rotation. Temporary fixation with Kirschner wires. Radiographic control in two planes followed by fixation with two or three lag screws. Removal of the medial fibular cortex, freshening of the lateral gutter, and fixation of the distal fibular fragments to tibia and talus with cortical screws. RESULTS: 20 arthrodeses in 19 patients were followed up for an average of 39 months (12-69 months). All arthrodeses were fused. In one patient a fibular pseudarthrosis was encountered. All arthrodeses healed in a correct position but one that consolidated with a pes equinus of 3 degrees . The average AOFAS (American Orthopedic Foot and Ankle Society) hindfoot score reached 78.5 points (40-86 points). A marked reduction of symptoms and satisfactory function were reported postoperatively by all patients. All would be willing to undergo surgery again.

Adult↗
PubMed2005

The global burden of group A streptococcal diseases.

The global burden of disease caused by group A streptococcus (GAS) is not known. We review recent population-based data to estimate the burden of GAS diseases and highlight deficiencies in the available data. We estimate that there are at least 517,000 deaths each year due to severe GAS diseases (eg, acute rheumatic fever, rheumatic heart disease, post-streptococcal glomerulonephritis, and invasive infections). The prevalence of severe GAS disease is at least 18.1 million cases, with 1.78 million new cases each year. The greatest burden is due to rheumatic heart disease, with a prevalence of at least 15.6 million cases, with 282,000 new cases and 233,000 deaths each year. The burden of invasive GAS diseases is unexpectedly high, with at least 663,000 new cases and 163,000 deaths each year. In addition, there are more than 111 million prevalent cases of GAS pyoderma, and over 616 million incident cases per year of GAS pharyngitis. Epidemiological data from developing countries for most diseases is poor. On a global scale, GAS is an important cause of morbidity and mortality. These data emphasise the need to reinforce current control strategies, develop new primary prevention strategies, and collect better data from developing countries.

Glomerulonephritis↗
PubMed2005

Intravenous anaesthetics inhibit nicotinic acetylcholine receptor-mediated currents and Ca2+ transients in rat intracardiac ganglion neurons.

The effects of intravenous (i.v.) anaesthetics on nicotinic acetylcholine receptor (nAChR)-induced transients in intracellular free Ca(2+) concentration ([Ca(2+)](i)) and membrane currents were investigated in neonatal rat intracardiac neurons. In fura-2-loaded neurons, nAChR activation evoked a transient increase in [Ca(2+)](I), which was inhibited reversibly and selectively by clinically relevant concentrations of thiopental. The half-maximal concentration for thiopental inhibition of nAChR-induced [Ca(2+)](i) transients was 28 microM, close to the estimated clinical EC(50) (clinically relevant (half-maximal) effective concentration) of thiopental. In fura-2-loaded neurons, voltage clamped at -60 mV to eliminate any contribution of voltage-gated Ca(2+) channels, thiopental (25 microM) simultaneously inhibited nAChR-induced increases in [Ca(2+)](i) and peak current amplitudes. Thiopental inhibited nAChR-induced peak current amplitudes in dialysed whole-cell recordings by approximately 40% at -120, -80 and -40 mV holding potential, indicating that the inhibition is voltage independent. The barbiturate, pentobarbital and the dissociative anaesthetic, ketamine, used at clinical EC(50) were also shown to inhibit nAChR-induced increases in [Ca(2+)](i) by approximately 40%. Thiopental (25 muM) did not inhibit caffeine-, muscarine- or ATP-evoked increases in [Ca(2+)](i), indicating that inhibition of Ca(2+) release from internal stores via either ryanodine receptor or inositol-1,4,5-trisphosphate receptor channels is unlikely. Depolarization-activated Ca(2+) channel currents were unaffected in the presence of thiopental (25 microM), pentobarbital (50 microM) and ketamine (10 microM). In conclusion, i.v. anaesthetics inhibit nAChR-induced currents and [Ca(2+)](i) transients in intracardiac neurons by binding to nAChRs and thereby may contribute to changes in heart rate and cardiac output under clinical conditions.

Acetylcholine↗
PubMed2005

Communicating asset risk: how name recognition and the format of historic volatility information affect risk perception and investment decisions.

An experiment examined how the type and presentation format of information about investment options affected investors' expectations about asset risk, returns, and volatility and how these expectations related to asset choice. Respondents were provided with the names of 16 domestic and foreign investment options, with 10-year historical return information for these options, or with both. Historical returns were presented either as a bar graph of returns per year or as a continuous density distribution. Provision of asset names allowed for the investigation of the mechanisms underlying the home bias in investment choice and other asset familiarity effects. Respondents provided their expectations of future returns, volatility, and expected risk, and indicated the options they would choose to invest in. Expected returns closely resembled historical expected values. Risk and volatility perceptions both varied significantly as a function of the type and format of information, but in different ways. Expected returns and perceived risk, not predicted volatility, predicted portfolio decisions.

Journal Article↗
PubMed2005

Platelet activation markers in patients with venous thromboembolism without predisposing factors.

A constant in vitro hypersensitivity of platelets (adenosine diphosphate) has been suggested as a risk factor for arterial and even venous thrombosis. Our aim was to determine phenotypic and functional alterations of platelets by flow cytometry as potential prothrombotic risk factors in patients with a history of unexplained spontaneous venous thrombosis. Forty-nine patients with a history of spontaneous venous thrombosis and no inherited or acquired thrombophilic risk factors were compared with a reference group of 39 healthy volunteers. Flow cytometry (FACS) was used to analyze the surface expression of CD62 (P-selectin) and CD63 in nonactivated platelets and after in vitro stimulation with adenosine diphosphate and thrombin receptor activator peptide 6. Mean fluorescence intensity of CD62 and CD63 surface expression as well as percentage of CD62 and CD63 positive cells and binding index differed in patients with a history of thrombosis compared with the reference group, but failed to reach statistical significance. Similar results were observed after in vitrostimulation with adenosine diphosphate and thrombin receptor activator peptide 6. In conclusion, the expression of CD62 and CD63 of resting and in vitro activated platelets could not be established as a risk factor for spontaneous venous thromboembolism.

Adenosine Diphosphate↗
PubMed2005

Peroneal tendon lesions caused by antiglide plates used for fixation of lateral malleolar fractures: the effect of plate and screw position.

BACKGROUND: Posterolateral antiglide plating of unstable AO-type B lateral malleolar fractures is biomechanically stronger than lateral plating and causes less wound healing problems and less frequent hardware removal. However, the distal end of the plate or the screws may cause peroneal tendinitis. The limits of safe hardware placement have not been established. METHOD: A retrospective analysis of 70 patients was done to determine hardware position and identify peroneal tendon lesions. An adjunct study involved dissection of the retromalleolar region in 10 embalmed cadaver specimens to study the anatomy of the osteosynovial peroneal groove. RESULTS: Thirty of 70 (43%) patients had the plate removed because of discomfort or signs of peroneal tendinitis. Peroneal tendon lesions were identified intraoperatively in nine of the 30 (30%) patients. Only two of these nine patients had felt symptoms preoperatively. Placement of the distal end of the plate distal to the proximal third of the lateral malleolus did not correlate with a peroneal tendon lesion. However, this placement combined with a screw in the most distal hole of the plate and a prominent screw head was strongly correlated with peroneal tendon lesions. In the anatomic specimens the shape of the osteosynovial part of the peroneal groove was uniform, but its length showed greater variation than the length of the foot. CONCLUSIONS: Antiglide plating of lateral malleolar fractures led to high rates of hardware removal and peroneal tendon lesions. Correlations were found to low placement of the plate together with a protruding screw head in the most distal hole of the plate. Distal screw placement should therefore be avoided or the hardware should be removed early. Absence of subjective signs of peroneal tendon irritation does not exclude even a major tendon lesion.

Ankle Injuries↗
PubMed2004

Dendritic polyamines: simple access to new materials with defined treelike structures for application in nonviral gene delivery.

Polycationic dendrimers are interesting nonviral vectors for in vitro DNA delivery. We describe a simple approach to the synthesis of dendritic polyamines with different molecular weights and adjustable flexibility (degrees of branching; DB). Both parameters influence the transfection efficiency and the cell toxicity of the polymer. Functionalization of hyperbranched polyethylenimine (PEI) by a two-step procedure generated fully branched pseudodendrimers (analogues of polypropylenimine (PPI) and polyamidoamine (PAMAM) dendrimers). The DNA transfection efficiencies observed for these polymers depended on the cell line investigated. The highest efficiencies were observed for polymers whose unfunctionalized PEI cores had molecular weights in the range M(w)=6000-25 000 g mol(-1). The cytotoxicity of the dendrimers generally rises with increasing core size. The data collected for NIH/3T3 and COS-7 cells indicate a maximum transfection efficiency at around 60 % branching for the PPI analogues, and at a PEI-core molecular weight of M(w)=25 000 g mol(-1). PAMAM functionalization of PEI (M(w)=5000 and 21 000 g mol(-1)) leads to polymers with little or no cytotoxity in the cell lines investigated.

Animals↗
PubMed2004

Methodological and quality issues in epidemiological studies of acute lower respiratory infections in children in developing countries.

Acute respiratory infections are the most important single cause of global burden of disease in young children globally and a major cause of child mortality. A recent review of studies reporting the incidence of acute lower respiratory infections (ALRI) in young children in the developing world was carried out by the WHO Child Health Epidemiology Reference Group in order to inform global burden of disease estimates. The review highlighted the low number of community-based longitudinal studies of ALRI incidence in young children which met minimum quality criteria. It underscored the need to give attention to issues of study design and the reporting of a basic minimum dataset which describes circumstances under which the studies were being conducted and the key design features of the study which may influence the ALRI estimate. This paper aims to provide methodological guidelines for the design, conduct, and reporting of epidemiological studies of ALRI in under-5s in developing countries. It discusses determinants of study quality related to both study design and statistical analysis and also issues requiring further research. It is hoped that these guidelines will stimulate further work in this field and encourage the publication of reports which contain sufficient data to permit a meaningful meta-analysis of the data, thus forming the basis of more reliable future estimates of global burden of ALRI.

Child, Preschool↗
PubMed2004

Statins as potential therapeutic agents in multiple sclerosis.

3-Hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase inhibitors (ie, statins) are oral cholesterol-lowering drugs. Statins are well tolerated and have an excellent safety record. These agents competitively inhibit HMG CoA reductase, which is the enzyme that catalyzes the conversion of HMG CoA to L-mevalonate. Although L-mevalonate is a key intermediate in cholesterol synthesis, several of its metabolites are involved in post-translational modification of specific proteins involved in cell proliferation and differentiation. Thus, independent of their cholesterol-reducing properties, statins have important pleiotropic biologic effects. Recent reports indicate that statins have anti-inflammatory and neuroprotective properties. Whether statins will be of clinical benefit for patients with multiple sclerosis and other neurodegenerative diseases of the central nervous system will only be known after they are evaluated in prospective randomized clinical trials.

Humans↗
PubMed2004

RNA interference: PCR strategies for the quantification of stable degradation-fragments derived from siRNA-targeted mRNAs.

mRNA targeted by siRNA is endogeneously cleaved into a 5'- and a 3'-fragment and finally degraded in cells. Little is known about the relative stability and degradation kinetics of these 5'- and 3'-fragments after the siRNA mediated first cut. We present a qRT-PCR protocol which allows the determination of the optimal time point for mRNA analyses, helping to avoid the generation of false positive effects in downstream experiments, such as microarray analysis, which may be caused by undegraded fragments of a siRNA-targeted mRNA.

Gene Silencing↗
PubMed2004

The avascular talus: revascularization in an animal model.

Avascular necrosis of bone such as the talus can lead to collapse and loss of function. To avoid this, early revascularization has been proposed as an important event. Revascularization can occur either by vessel growth directly through the bony surface, or by vessel growth into the periosteum or ligaments with secondary reconnection to the bone. The ability to attract new vessels (angiogenesis) of the bony surface and the connective tissue was compared in an animal model. A talus isograft (all cortical surface, periosteum, and ligaments remaining; n = 11) or a sector of a femoral head isograft (cancellous surface, no connective tissue; n = 12) of adult mice was implanted into dorsal skinfold chambers of mice of the same strain. The implants were observed by intravital microscopy every 12 hours. First indicators of angiogenesis were hemorrhages around the implants (tali: 11 of 11, 72 +/- 12 hours; femoral heads: 6 of 12, 84 +/- 24 hours). Next, a sudden redness of the transplant indicated marrow hemorrhage (tali: 9 of 11 after 84 +/- 36 hours; femoral heads: 10 of 12 after 96 +/- 36 hours). Histology showed clear growth of capillaries into the cancellous surface of the femoral heads and possible growth of capillaries into the ligament stumps (tali). However, there was widespread necrosis of the marrow cells indicating failure of recirculation. A cancellous bony surface as well as the soft tissues attached to the bone provided a stimulus to rapid revascularization of the grafts. This model was able to evaluate differing rates of early partial revascularization for various bone surfaces, which may have implications for studying treatment options for certain fracture dislocations (e.g., in the talus).

Animals↗
PubMed2004

Trimalleolar fractures with impaction of the posteromedial tibial plafond: implications for talar stability.

BACKGROUND: Trimalleolar fractures usually include a lateral malleolar fracture, a triangular fracture of the posterolateral corner of the tibial plafond, and a horizontal or oblique fracture of the medial malleolus. A subtype of a trimalleolar fracture is reported, differing in the shape and extent of the medial malleolar fracture and the posterior lip fracture, with implications for treatment. METHODS: In a 3-year period, 10 patients were treated for a trimalleolar fracture with a multifragmentary transverse fracture of the entire posterior tibial lip, including the posterior colliculus of the medial malleolus. The radiographs of all patients showed a pathognomonic double-contour or flake-fragment sign above the medial malleolus. One patient's posteromedial fracture was not initially recognized and he had a standard lateral fracture repair. A double posterior approach was used in nine patients, with fracture repair proceeding from medial to lateral. Intraoperatively, eight of nine patients had impacted osteochondral fragments at the posteromedial corner of the tibial plafond that blocked anatomic reduction and allowed posteromedial subluxation of the talus. RESULTS: Nine patients had anatomic reconstruction of the posteromedial corner. All fractures healed, and function was normal at one year. One patient had moderate loss of joint space. The patient with the malunited fracture developed symptomatic posteromedial instability of the talus and required an osteotomy of the malunited fragment. He had a good result at 18 months. CONCLUSIONS: This unique subtype of trimalleolar fracture has distinct radiological features and implications for the strategy of the operative treatment. If recognized immediately and treated appropriately, the results were excellent. If missed initially, reconstructive osteotomy was possible and led to a good result.

Adult↗
PubMed2004

Time expenditure in patient-related care provided by specialist palliative care nurses in a community hospice service.

Although the importance of specialist palliative care in home care programmes for terminally ill patients is well known, German community hospice services did not begin to employ nurses who had specialized in palliative care until the early 1990s. The general tasks of these nurses are sufficiently well defined, but no comprehensive data of their daily workload are available in Germany to date. The present article examines time expenditure in direct patient-related care at the community-based hospice service in Mainz, Germany, by analysing time registration sheets concerning 351 patients who received care from January 2000 until December 2002. Fifty-five per cent of care time spent on each individual patient was in direct contact with that patient and/or his or her relatives, 20% of the time was spent on networking and other related tasks, 17% on travelling and 8% on bereavement counselling. Activities in direct patient contact were allotted to pain and symptom control (36.4%) and psychosocial support of the patient (32.4%) or his or her relatives (27.1%), whereas nursing issues played a minor role (4%).

Adolescent↗