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Biomedical subjects

U Kramer

Publications and source records attributed to U Kramer.

At least 19 recordsLinked to original sources
PubMed2003

Radiopaque markers in endovascular stents--benefit and potential hazards.

AIM: The primary objective of this study was to evaluate the impact of radiopaque markers on stent visibility. The secondary objective was to investigate the impact of such radiopaque markers on localized corrosion at the stent corpus-marker interfaces. MATERIAL AND METHODS: The radiopacity of the following stents was evaluated at different fluoroscopy modes (spotfilm, continuous fluoroscopy, 15 p/s, 7.5 p/s, 3 p/s): Memotherm Flexx (FX), Memotherm Luminexx (LX)(Bard), SMART (SM), SMARTeR (SMR)(Cordis). Four readers evaluated a total of 3200 images (160 per stent per fluoro mode) according to the following radiopacity score (RS): 0 = no stent visible, 1 = poor, 2 = acceptable, 3 = good, and 4 = very good stent visibility. LX and SMR stents (n = 5/group) were subjected to potentiodynamic polarization testing in de-aerated Hanks salt solution at 37 degrees C using a potentiostat. Palmaz-Schatz stents (n = 3) were used as the control group for comparative evaluation. The corrosion current density (I corr ) and the breakdown value (E bd ) were compared parameters of interest. RESULTS: At the spotfilm mode the LX, the SM and the SMR were rated well to very well visible in 99 %, 96 %, 96 %, and the FX only in 64 %. At 7.5 p/s (standard fluoro mode) the LX was considered to be well to very well visible in 77 %, followed by the SMR in 12.5 %, the SM in 1 %, and the FX in 0 %. The SMR stents exhibited the highest E bd values (802 +/- 112 mV vs SCE), while the LX stents exhibited the lowest E bd values (155 +/- 38 mV vs SCE). Also, the average E bd values for the SMR stents were better than those exhibited by the PS stents (503 +/- 107 mV vs SCE). CONCLUSION: Stent radiopacity can be increased significantly with the help of radiopaque markers (p < 0,0001 LX vs. FX). However, the surface condition of the stent corpus and the mode of attachment of the marker onto the corpus may have a significant impact on the uniformity of the final corrosion behavior. It is not feasible to determine the clinical impact of this localized corrosion behavior from this in vitro study. Further experimentation is recommended to ascertain the same.

Coated Materials, Biocompatible↗
PubMed2003

Androgens shorten the longevity of women: sopranos last longer.

Earlier we found that longevity of castrati was identical to that of intact singers. These findings were in disagreement with the prevailing concept that testosterone might shorten life and might be responsible for the shorter life expectancy of men compared to women. We have now continued our research into the life expectancy of singers, considering them as a paradigm of nature to investigate life-long effects of sex hormones, and resulting in the finding that sopranos, being more oestrogenised, live significantly longer than altos who are more androgenised, while basses, more androgenised, show a tendency towards a longer life than tenors, who are less androgenised. These findings, supported by results of epidemiological investigations indicate that women are protected from cardiovascular diseases, diabetes and osteoporosis by higher oestrogen levels, while the same effect maybe exerted in men by testosterone.

Aged↗
PubMed2001

Subacute myocardial infarction: assessment by STIR T2-weighted MR imaging in comparison to regional function.

PURPOSE: Increased T2 signal intensity (SI) can be regularly observed in myocardial infarction. However, there are controversial reports about the relationship of elevated T2 SI to myocardial viability and some authors propose that high T2 SI serves as a sign of irreversible myocardial injury. This study investigates increased T2 SI compared to myocardial function in patients with reperfused subacute myocardial infarction. Preserved function was used as criterion for viability. METHODS: Ten healthy volunteers and 17 patients with myocardial infarction and patent infarct related coronary artery were examined on a 1.5 T Magnetom Vision system (Siemens). For T2-weighted MR imaging a breath-hold STIR sequence with dark-blood preparation was used. Cine FLASH 2D imaging was applied to assess myocardial function. Signal-to-noise (S/N) in STIR T2 images was measured in normal and infarcted regions and subsequently identified by two independent observers. Based on a 20 segment model of the left ventricle findings were compared to regional myocardial function. RESULTS: Elevated STIR T2 SI was found in all 17 patients and observed in 27% (204/754) of segments. S/N of normal myocardium was 5.1 +/- 0.7 in volunteers and 4.9 +/- 0.8 in patients (P = NS). Infarcted myocardium presented with significantly increased S/N 12.8 +/- 1.9 (P < 0.0001). Significant transmural elevation of T2 SI was noted in 32% of segments with preserved systolic function. CONCLUSION: Increased STIR T2 SI can be observed transmurally in post-ischemic myocardial regions with preserved function. It therefore cannot be used as an exclusive marker for the non-viable region.

Aged↗
PubMed2001

Absence seizures aggravated by valproic acid.

PURPOSE: To report on pediatric patients with absence epilepsy who experienced absence seizure aggravation while receiving valproic acid (VPA). METHODS: The charts of all children from four pediatric epilepsy clinics receiving VPA for absence epilepsy were reviewed. Patients were evaluated and followed up between 1994 and 2000. RESULTS: Eight cases (six boys) of absence seizure aggravation were detected. Mean age at seizure onset was 5.8 years (range, 3-12 years). Six patients had simple absence seizures, one had myoclonic absences, and one had absences with automatisms. The electroencephalogram in all cases depicted generalized 3-Hz spike-and-wave activities. All eight patients experienced an increase in the frequency of absence seizures within days of VPA introduction. Dose increments resulted in further seizure aggravation. Serum levels of VPA were within therapeutic range in all patients. No case was attributed to VPA-induced encephalopathy. All patients improved on VPA discontinuation. In five children, VPA was reintroduced, resulting in further seizure aggravation. CONCLUSIONS: VPA can occasionally provoke absence seizure aggravation in patients with absence epilepsy.

Acute Disease↗
PubMed2001

Transient oromotor deficits in children with benign childhood epilepsy with central temporal spikes.

PURPOSE: To describe transient oromotor deficits in benign childhood epilepsy with centrotemporal spikes (BCECTS), an idiopathic age-specific epileptic syndrome with a benign course. METHODS: Five children with BCECTS and intermittent dysarthria and drooling not in the context of typical clinical seizures are presented. RESULTS: The periods of oromotor deficits correlated with increased seizure frequency in all children. Concomitant EEGs that were recorded during periods of dysarthria in four of the children revealed focal electrographic seizures. The reported children did not differ from other patients with BCECTS in any other respect. CONCLUSIONS: Transient oromotor dysfunction is a rare ictal phenomenon that occurs in children with BCECTS with no other unique clinical features.

Adolescent↗
PubMed2001

[2D-phase contrast flow evaluation and contrast-enhanced MR angiography for perioperative assessment of internal mammary artery grafts].

PURPOSE: To evaluate LV functional parameters, graft flow and patency in patients with IMA grafts using a combined MR protocol with phase-contrast technique and contrast enhanced MR angiography. MATERIAL AND METHODS: Using a 1.5 T MR system 27 patients with 27 left internal mammary artery (LIMA) and 41 venous grafts were examined before and 6 months after CABG surgery. A T(1)w-TSE sequence (slice thickness 5 mm) was applied for morphological imaging. LV function (EF, CO) was evaluated on cine images (segmented FLASH 2D, TR(eff) 11 ms, TE 4.8 ms, flip angle 25 degrees ). A phase-contrast FLASH 2D (TR 24 ms, TE 5 ms, flip angle 20 degrees ) sequence was applied for aortic and IMA flow measurements. Postoperatively, a contrast enhanced FLASH 3D MR angiography (TR 3.8 ms, TE 1.4 ms, flip angle 30 degrees ) with 25 ml Gd-DTPA was performed to assess bypass patency. RESULTS: In patients with reduced LV function (ejection fraction < 50 %) an improvement of the ejection fraction from 38.4 +/- 10.3 % to 49.8 +/- 15.3 % (p < 0.05) was found postoperatively. LIMA grafts were occluded in 1/27 patients, while 6/41 venous grafts were occluded. Distal LIMA anastomoses were demonstrated in 33 % by MRA. Flow of LIMA decreased from 21.2 +/- 11 ml/min/m(2) preoperatively to 14.4 +/- 9.6 ml/min/m(2) postoperatively (p < 0.01). CONCLUSION: MR imaging allows accurate combined assessment of LV function, bypass patency and flow. The protocol of this study may be applicable for perioperative follow-up studies in patients after CABG surgery.

Aged↗
PubMed2001

Surgical treatment of hypothalamic hamartoma and refractory seizures: a case report and review of the literature.

Refractory gelastic seizures are often associated with hypothalamic hamartoma (HH). Presurgical evaluation in such children often points to a distinct cortical region as the source of the seizures. A case of a child with HH and refractory seizures is presented. Video-EEG monitoring revealed a well-defined epileptic focus in the left frontal region. In accordance with the current understanding of the nature of hamartoma-related seizures, the hamartoma was resected. Follow-up evaluations revealed a marked improvement in seizure frequency and global functioning.

Child, Preschool↗
PubMed2001

No evidence of epilepsy following endoscopic third ventriculostomy: a short-term follow-up.

Patients with ventriculo-peritoneal shunts are predisposed to various complications, including the appearance of seizures over time. The high rate of complications prompted an interest in alternative procedures such as endoscopic third venticulostomy (ETV) in selected patients. From 1996 to 1998, 42 patients underwent ETV in our center. Of the 27 operated children who were followed for an average of 32 months, none experienced seizures during that time. We conclude that, in addition to other benefits, ETV minimizes the risk of epilepsy following shunt insertion, probably due to the lack of direct cortical insult.

Child↗
PubMed2001

Prognostic significance of hyperechogenic lesions in the basal ganglia and thalamus in neonates.

Neonatal cranial ultrasonography at times reveals hyperechogenic lesions in the basal ganglia and thalamus. These lesions have been attributed to a wide variety of pathologic states, among them toxoplasmosis, rubella, cytomegalovirus, and herpes simplex (TORCH) infections, chromosomal abnormalities, and asphyxia. The clinical significance in terms of the neurodevelopmental outcome of this radiologic abnormality is unknown. We performed a developmental evaluation on 16 children aged 2 to 6 years in whom neonatal cranial ultrasonography had demonstrated hyperechogenic lesions in the basal ganglia or thalamus and had no other neurodevelopmental risk factors. There was no significant difference between the average Developmental Quotient of the target population and the normal population in regard to developmental status. We conclude that in our population, an isolated finding of hyperechogenic lesions in the basal ganglia is probably not a predictor of poor neurodevelopmental outcome.

Basal Ganglia↗
PubMed2001

[Benign childhood epilepsy with centro-temporal spikes].

Benign childhood epilepsy with centro-temporal spikes is a specific pediatric syndrome, characterized by typical clinical symptoms including hemifacial convulsions which tend to generalize in sleep. There is no loss of consciousness. The typical EEG shows blunt diphasic spikes, localized in the rolandic or mid-temporal area. The spikes are high voltage and increase in drowsiness and sleep. In all these patients there is a normalization of the EEG and cessation of seizures in a few years, even without treatment. All these pediatric patients recover before adulthood.

Anticonvulsants↗
PubMed2000

[Phenobarbital coma for psychogenic status epilepticus].

Among patients seen for epileptic seizures, there is a subgroup of those who do not have epilepsy but suffer from psychogenic paroxysmal events which mimic epileptic seizures. The differential diagnosis between them is of the utmost importance, as incorrect diagnosis of seizures subjects the patient to incorrect management. In the case psychogenic status epilepticus, the treatment may endanger the patient. We report 3 women, aged 20, 20 and 28 and a man aged 24 with psychogenic status epilepticus admitted to an intensive care unit and treated by induction of phenobarbital coma when other antiepileptic medication failed.

Adult↗
PubMed2000

Unprovoked seizures after complex febrile convulsions.

Children with complex febrile convulsions bear a higher risk of developing epilepsy than children with simple febrile convulsions. Complex febrile convulsions are defined by the presence of prolonged seizures, partial seizures and multiple seizures occurring during the same day. The aim of this study is to delineate the relative significance of each of the three criteria defining complex febrile convulsions. Fifty-seven out of 477 children (12%) admitted for febrile convulsions had complex febrile convulsions and normal neurological examination. Follow-up was available for 48 (84%) of them. Thirteen of these 48 (27%) had epilepsy at follow-up. The mean age of seizure onset among the patients with subsequent afebrile seizures was significantly lower than the rest (10.8 months versus 16.8 months). The patients with partial febrile convulsions showed a trend toward a higher risk (45%) of developing epilepsy than the patients with multiple febrile convulsions (21%).

Child↗
PubMed2000

Mental retardation subsequent to refractory partial seizures in infancy.

Whether seizures are the direct cause of cognitive deterioration in epileptic children is undetermined. This retrospective study aimed to delineate a subgroup of pediatric patients with cognitive deterioration and refractory seizures in the absence of recognized causes for mental retardation. Of the 80 children identified as having mental retardation and refractory seizure disorder, seven (8.7%) had normal cognitive development until at least 1 year of age. Their metabolic status was normal. Five of them suffered repeated frequent partial seizures with onset in the first year of life and two had repeated episodes of status epilepticus. All seven had similar characteristics of early onset partial seizures, six of them had partial seizures secondarily generalized and one had complex partial seizures. The time of peak cognitive deterioration correlated with increases in seizure frequency during that period. Evaluation revealed a well-defined epileptic focus in the absence of neuroimaging abnormality except for hippocampal atrophy in the two children with complex partial seizures and a small vascular malformation in one child. Uncontrolled partial seizures in the first months of life may result in cognitive deterioration.

Adolescent↗
PubMed2000

Alternating hemiplegia of childhood: clinical manifestations and long-term outcome.

We present our analysis of 44 patients with alternating hemiplegia of childhood. The clinical course usually consisted of three phases. The first was dominated by abnormal eye movements and dystonic episodes, the second by hemiplegic spells and psychomotor regression, and the third by persistent developmental delay and fixed neurologic deficits. The age of onset was 0-54 months (mean = 7.9 +/- 13 months). The presenting signs included abnormal ocular movements in 65%, dystonia in 60%, and hemiplegia in 32%. Patients with an early onset of the disorder and an early appearance of hemiplegic spells faired the poorest developmentally. Developmental delay was present in 91%, ataxia in 68%, choreoathetosis in 50%, and seizures in 18%. Laboratory investigations suggested mitochondrial abnormalities and cerebrovascular dysfunction in several patients. Numerous therapies were largely ineffective. Flunarizine reduced the duration, severity, and frequency of the hemiplegic attacks in 78%. Patients who received flunarizine did not differ developmentally from those who did not. Our data suggest that flunarizine does not adversely affect and may favorably influence the outcome in patients with alternating hemiplegia of childhood. Additionally, the occurrence of autosomal-dominant cases of the syndrome, although rare, suggests that, in addition to mitochondrial dysfunction, genetic factors may be important.

Adolescent↗
PubMed2000

Outcome of infants with unilateral Sturge-Weber syndrome and early onset seizures.

Patients with Sturge-Weber syndrome often present with seizures during the first year of life. Currently, only patients with clinically significant seizures who do not respond to medical treatment are candidates for early epileptic surgery. However, a delay of surgical treatment may result in cognitive deterioration. We studied the correlation between parameters and outcome of seizures to re-examine the criteria for early epilepsy surgery. We performed a retrospective chart review combined with telephone interviews of parents of all Israeli infants with unilateral Sturge-Weber syndrome and early onset seizures, and we examined whether age of seizure onset and seizure intensity were correlated with cognitive level and the degree of hemiparesis at follow-up. We recruited a total of 15 patients with unilateral Sturge-Weber syndrome and early onset seizures, five of whom underwent epilepsy surgery. The mean follow-up period of all the patients was 15 years: six patients had normal intelligence, four had borderline cognitive level, three had mild mental retardation and two had moderate mental retardation. Eight of the ten non-operated patients still experience seizures at follow-up. Cognitive delay was significantly correlated with seizure intensity in the early period, but not with the age of seizures onset, the degree of hemiparesis, or the presence of ongoing seizures. We conclude that high seizure intensity in young patients with Sturge-Weber syndrome is a prognostic marker for mental deterioration.

Age of Onset↗
PubMed2000

[Variability in the MR tomographic determination of myocardial function and perfusion parameters in health subjects].

PURPOSE: The aim of the study was to evaluate myocardial function and perfusion patterns using magnetic resonance imaging in normal subjects. MATERIALS AND METHODS: 22 healthy volunteers were examined. Cine-mode acquisitions along all three axes of the heart were generated and perfusion was measured on a mid-ventricular short-axis view. Myocardial wall thickening was scored and contrast enhancement during the first pass was analysed. RESULTS: For myocardial wall thickening increasing values from base (24-86%) to apex (63-106%) were found. Contrast enhancement patterns showed regional variability. In addition marked individual differences were detectable. CONCLUSION: Perfusion patterns should be interpreted only in combination with functional parameters. Standard values for perfusion measurements cover very large range as a result of the high individual variability.

Adult↗
PubMed2000

Interferon consensus sequence binding protein confers resistance against Yersinia enterocolitica.

Interferon consensus sequence binding protein (ICSBP)-deficient mice display enhanced susceptibility to intracellular pathogens. At least two distinct immunoregulatory defects are responsible for this phenotype. First, diminished production of reactive oxygen intermediates in macrophages results in impaired intracellular killing of microorganisms. Second, defective early interleukin-12 (IL-12) production upon microbial challenge leads to a failure in gamma interferon (IFN-gamma) induction and subsequently in T helper 1 immune responses. Here, we investigated the role of ICSBP in resistance against the extracellular bacterium Yersinia enterocolitica. ICSBP(-/-) mice failed to produce IL-12 and IFN-gamma, but also IL-4, after Yersinia challenge. In addition, granuloma formation was highly disturbed in infected ICSBP(-/-) mice, leading to multiple necrotic abscesses in affected organs. Consequently, ICSBP(-/-) mice rapidly succumbed to acute Yersinia infection. In vitro treatment of spleen cells from ICSBP(-/-) mice with recombinant IL-12 (rIL-12) or rIL-18 in combination with a second stimulus resulted in IFN-gamma induction. In experimental therapy of infected ICSBP(-/-) mice, we observed that administration of rIL-12 induced IFN-gamma production which was associated with improved resistance to Yersinia. In contrast, treatment with rIL-18 failed to enhance endogenous IFN-gamma production but nevertheless reduced bacterial burden in ICSBP(-/-) mice. Although cytokine therapy with rIL-12 or rIL-18 ameliorated the course of Yersinia infection in ICSBP(-/-) mice, both cytokines failed to completely restore impaired immunity. Taken together, the results indicate that the transcription factor ICSBP is essential for efficient host immune defense against Yersinia. These results are important for understanding the complex host immune responses in bacterial infections.

Animals↗