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Biomedical subjects

E Keller

Publications and source records attributed to E Keller.

At least 73 records · Page 4Linked to original sources
PubMed2000

[Clinical management of acute head injury].

Patients after acute head injury are susceptible to secondary insults and therefore to secondary brain injury. A comprehensive approach, starting at the site of the accident, followed by emergency diagnosis and treatment in the appropriate emergency department of the trauma centre, intensive care and specific neurorehabilitation is the only way to minimise sequelae of primary brain lesions, prevent secondary brain damage and establish optimum frame conditions with respect to recovery from non-definite brain damage.

Accidents↗
PubMed2000

Proton MR spectroscopy detects a relative decrease of N-acetylaspartate in the medial temporal lobe of patients with AD.

BACKGROUND: The reduction of N-acetylaspartate (NAA) detected by proton MR spectroscopy (1H-MRS) represents a robust but unspecific marker for neuronal loss or dysfunction. OBJECTIVE: To apply 1H-MRS in two brain regions that reflect the characteristic spatial distribution of neuronal loss in AD. These regions are the medial temporal lobe (MTL), which is affected early in AD, and the primary motor and sensory cortex (central region), which is affected late in the disease and might serve as an intraindividual control region in mild to moderate disease stages. METHODS: Twenty patients and 18 volunteers underwent 1H-MRS in both brain areas. The metabolic ratios of NAA/creatine and choline/creatine were determined. Additionally, the metabolic ratios of the MTL were divided by the ratios of the central region to assess the relative change in the MTL in individual subjects. All ratios were correlated with psychometric test scores. RESULTS: A significant reduction of NAA/creatine and choline/creatine ratios was detected in the MTL of patients with AD. In the central region, no significant difference between the groups was found. NAA/creatine (MTL/central region) was reduced in patients with AD and showed a correlation with the Mini-Mental State Examination and the cognitive part of the Alzheimer Disease Assessment Scale scores. Choline/creatine (MTL/central region) did not show a significant difference between groups. CONCLUSION: Assessing the distribution of NAA/creatine reduction guided by the expected neuropathologic change can improve the role of 1H-MRS in the assessment of AD. The disease severity can be monitored by relative reduction of NAA/creatine in the MTL in comparison with an intraindividual unaffected control region.

Aged↗
PubMed2000

Changes in cerebral blood flow and oxygen metabolism during moderate hypothermia in patients with severe middle cerebral artery infarction.

OBJECT: Moderate hypothermia has been reported to be effective in the treatment of postischemic brain edema. The effect of hypothermia on cerebral hemodynamics is a matter of controversial discussion in literature. Clinical studies have yet to be performed in patients with ischemic stroke after induction of hypothermia. METHODS: Measurements during mild hypothermia (33-34 degrees C) were made in six patients with severe ischemic stroke involving the middle cerebral artery territory. Hypothermia was induced as soon as possible and maintained for 48 to 72 hours. Cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO2) were estimated by a new double-indicator dilution method. Measurements of CBF were made during normothermia, immediately after induction of hypothermia, at the end of hypothermia, and after rewarming. A total of 19 measurements of CBF and jugular bulb O2 saturation were made. Immediately after induction of hypothermia, CBF decreased in all patients. During late hypothermia, CBF improved in patients who survived but remained diminished in the two patients who died. Reduced CMRO2 levels were observed during all phases of hypothermia in all but one case. CONCLUSIONS: Preliminary oberservations indicate that moderate hypothermia seems to reduce CMRO2. Immediately after induction of hypothermia, CBF may decrease in all patients. During late hypothermia CBF seems to recover in patients with good outcome but remains diminished in patients who die. Serial bedside CBF measurements with the new double-indicator dilution technique may be useful to describe cerebral hemodynamic characteristics in patients with severe ischemic stroke during hypothermia.

Adult↗
PubMed2000

Ultra-fast three-dimensional MR perfusion imaging of the entire brain in acute stroke assessment.

We sought to evaluate a three-dimensional (3D) whole-brain perfusion technique based on echo-shifting (PRESTO) for its performance in evaluation of acute stroke. Twenty-six patients were scanned within 6 hours after onset of hemispheric symptoms, and the results were compared with results of diffusion-weighted imaging (DWI) and digital subtraction angiography (DSA). The signal-to-noise ratio of the images was 61 +/- 3 pre-contrast and 47 +/- 3 at the bolus peak. Brain coverage on perfusion parameter maps was 95% +/- 2% compared with that displayed on T2-weighted images, with only minor artifacts related to susceptibility at the skull base. Measured regional cerebral blood volume (rCBV) reduction closely correlated to lesion size on initial DWI and to final clinical outcome (P = 0.006), consistent with results previously reported for 2D perfusion methods. Mismatches between DWI and perfusion imaging characterized the total extent of tissue at risk, and the contrast timing correlated with the amount of collateral circulation as shown on DSA. In conclusion, 3D imaging using the PRESTO technique permits high-quality perfusion imaging of the entire brain.

Adolescent↗
PubMed2000

Immunohistochemical analysis of cerebral cortical and vascular lesions in the primate Microcebus murinus reveal distinct amyloid beta1-42 and beta1-40 immunoreactivity profiles.

Recent reports have shown that amyloid beta deposits in the brains of Alzheimer's disease patients consist mainly of two distinct species of amyloid beta protein (Abeta) with different C-termini, Abeta1-42 (Abeta42) and Abeta1-40 (Abeta40). The nature of the Abeta species in Microcebus murinus brain was investigated immunocytochemically using polyclonal antibodies with clear specificity for the Abeta42 and Abeta40 C-termini. The cortical vascular deposits were immunopositive for both Abeta42 and Abeta40. However, most of the diffuse plaques were strongly positive for Abeta42 whereas only a subset of deposits were positive for Abeta40. Numerous cortical plaques were Abeta42-immunopositive but tested negative for Abeta40. This suggests that Abeta42 is probably associated with early stages of plaque maturation. This neuropathological feature reminiscent of that observed in brains affected by Alzheimer's disease further supports the idea that M. murinus could be used as a potential model of the early stages of this neurological disease.

Amyloid beta-Peptides↗
PubMed2000

Detectability and detection rate of acute cerebral hemisphere infarcts on CT and diffusion-weighted MRI.

Our purpose was to compare the detectability and detection rate of acute ischaemic cerebral hemisphere infarcts on CT and diffusion-weighted MRI (DWI). We investigated 32 consecutive patients with acute hemisphere stroke with unenhanced CT and DWI within 6 h of stroke onset. The interval between CT and DWI ranged from 15 to 180 min (mean 60 min). Infarct detectability on CT and DWI was determined by comparing the initial CT, DWI and later reference images in a consensus reading of five independent examiners. The "true" detection rate was assessed by analysing all single readings. Two patients had intracerebral haematomas on DWI and CT and were excluded. There were 27 patients with ischaemic infarcts; all were visible on DWI and proven by follow-up. DWI was negative in three patients without a final diagnosis of infarct (100% sensitivity, 100% specificity, chi2 = 30, P < 0.0001). Ischaemic infarcts were visible on 15 and not seen on 12 CT studies (55 % sensitivity, 100% specificity, chi2 = 1.48, P = 0.224). With regard to the single readings (30 examinations x 5 examiners = 150 readings), 63 CT readings were true positive and 72 false negative (sensitivity 47 %, specificity 86%, chi2 = 2.88, P = 0.089). Of the DWI readings 128 were true positive and 7 false negative (sensitivity 95%, specificity 87 %, chi2 = 70.67, P < 0.0001). Interobserver agreement was substantial for CT (chi = 0.72, 95 % confidence interval, 0.6-0.84) and DWI (chi = 0.82, 95 % confidence interval, 0.46-1). Taken together, detectability and detection rate of acute (< 6 h) hemisphere infarcts are significantly higher with DWI than with CT.

Brain↗
PubMed2000

Fluorine-18 fluorodeoxyglucose PET in infectious bone diseases: results of histologically confirmed cases.

The aim of this study was to evaluate the clinical use of fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) in acute and chronic osteomyelitis and inflammatory spondylitis. The study population comprised 21 patients suspected of having acute or chronic osteomyelitis or inflammatory spondylitis. Fifteen of these patients subsequently underwent surgery. FDG-PET results were correlated with histopathological findings. The remaining six patients, who underwent conservative therapy, were excluded from any further evaluation due to the lack of histopathological data. The histopathological findings revealed osteomyelitis or inflammatory spondylitis in all 15 patients: seven patients had acute osteomyelitis and eight patients had chronic osteomyelitis or inflammatory spondylitis. FDG-PET yielded 15 true-positive results. The tracer uptake correlated with the histopathological findings in each case. Bone scintigraphy performed in 11 patients yielded ten true-positive results and one false-negative result. Follow-up carried out on two patients revealed normal or clearly reduced tracer uptake, which correlated with a normalisation of clinical data. In early postoperative follow-up it was impossible to differentiate between postsurgical reactive changes and further infection using FDG-PET. It is concluded that acute and chronic osteomyelitis of the peripheral as well as the central skeleton can be detected using FDG-PET. Osteomyelitis can be differentiated from soft tissue infection surrounding the bone. Unlike computed tomography and magnetic resonance imaging, FDG-PET is not affected by metal implants used for fixing fractures. FDG-PET demonstrated promising initial results with respect to treatment monitoring. Nevertheless, in the early postoperative phase FDG-PET seems to be of limited value owing to unspecific tracer uptake.

Adult↗
PubMed2000

The human forebrain has discrete estrogen receptor alpha messenger RNA expression: high levels in the amygdaloid complex.

Estrogen is considered to play an important role in neuropsychiatric disorders and the estrogen receptors mediate the action of the hormone. In the present study, the messenger RNA expression pattern of the estrogen receptor alpha subtype was identified in the post mortem human brain. High stringent in situ hybridization histochemistry was performed using a riboprobe specific for the estrogen receptor alpha subtype. The human brain was mainly characterized by abundant estrogen receptor alpha messenger RNA expression in the amygdala and hypothalamus, but labeling (lower) was also found in the extended sublenticular amygdala, cerebral cortex, and hippocampus. In the amygdala, the estrogen receptor alpha messenger RNA was preferentially expressed in medially-localized nuclei suggesting that estrogen regulates distinct human amygdala-mediated functions. The Cynomologous monkey brain was also examined in the present study and a similar distribution of the estrogen receptor alpha messenger RNA signal was observed in the human and monkey brain. However, the primate expression pattern differed in part from the known distribution in the rat. The current results show that estrogen receptor alpha messenger RNA is expressed in discrete areas of the human brain not only related to neuroendocrine function, but also emotion, memory, and cognition, which is consistent with the hypothesized involvement of estrogen in schizophrenia, affective disorders, and Alzheimers disease.

Adolescent↗
PubMed2000

The human brain has distinct regional expression patterns of estrogen receptor alpha mRNA isoforms derived from alternative promoters.

The human estrogen receptor (ER) alpha gene is transcribed from multiple promoters, generating mRNA isoforms with unique 5' ends in the untranslated region. In the present study, alternative promoters were shown to regulate the ERalpha gene expression in different neuronal populations of the human brain. By using in situ hybridization histochemistry, the A and B promoters, but not the C promoter, in the ERalpha gene were found to be active in the human forebrain. The mRNA isoform transcribed from the A promoter was expressed in low levels in most of the brain areas where ERalpha mRNA was present. In contrast, the B promoter mRNA isoform was more restricted, localized predominantly in high-expressing ERalpha mRNA regions. The gross anatomical distribution of the different mRNA isoforms analyzed with RT-PCR generally supported the results obtained by the in situ hybridization. Estrogen is known to modulate many different brain functions, such as neuroendocrine events associated with reproduction, mood, and cognition, likely to be mediated by different neuronal populations. Thus, the current findings of alternative ERalpha promoter expression in distinct neuronal populations suggest that multiple promoter usage is a possible mechanism to achieve differentiated regulation of the ERalpha expression, dependent on the cell phenotype and consequently the functions mediated by the specific neuron.

Adolescent↗
PubMed2000

Comparison of fresh frozen plasma with a standardized serum protein solution following therapeutic plasma exchange in patients with autoimmune disease: a prospective controlled clinical trial.

The aim of the study was the comparison of the influence of fresh frozen plasma (FFP) (Freiburg, Germany) and Biseko, Biotest Pharma GmbH (Dreieich, Germany), as a plasma substitute (a standardized, virus inactivated human serum protein solution) on the coagulation factors, inhibitors, proteins, and complement factors in the plasma of autoimmune disease patients following membrane plasma separation. Patients (n = 24) with autoimmune disease were randomized to receive either FFP or Biseko for membrane plasma separation therapy. During each plasma exchange, 100% of the plasma volume was replaced by the respective substitute. Plasma exchange volume was performed once daily for 3 days. Target test parameters of the coagulation system were fibrinogen, fibrinopeptide A, factor VIII (FVIIIC), von Willebrand factor antigen (vWFAg), partial thromboplastin time (PTT), thromboplastin time (Quick value), and antithrombin (AT III). The immunoglobulins were IgG, IgA, and IgM and C-reactive protein (CRP). The thrombocytes were platelet factor 4 (PF4), and complement factors were C3 and C4. Biseko was well tolerated with 1 mild adverse drug reaction (ADR) (n = 1) while FFP gave rise to ADR on 7 occasions (n = 4). Statistically significant differences in the 2 groups were observed for fibrinogen, PTT, Quick value, and AT III. From the clinical point of view, all fluctuations and differences in parameter levels remained clinically silent. The differences had no clinical consequences. Reflecting on a potential decrease in the risk of infections in comparison to FFP therapy and the lower rate of adverse drug reactions, it is possible to postulate an advantage of Biseko for plasma exchange therapy.

Adult↗
PubMed2000

Dietary fat intakes in infants and primary school children in Germany.

We report dietary fat intake data in groups of infants and children in Germany. A group of 148 healthy infants was followed prospectively from birth through the first year of life. After birth, 78.9% of infants were breast-fed; 50% were breast-fed at 3 mo and 9. 8% were breast-fed at 12 mo. Infant formula was given to 22% of infants after birth, 53% at 3 mo, and 58% at 12 mo. Complementary foods were consumed by 16% of infants at 3 mo, 97% at 6 mo, and 98-100% at 7-12 mo. In non-breast-fed infants, mean dietary fat intakes were 44.8%, 42.9%, 37.4%, and 35.7% of energy intake at the ages of 1, 4, 6, and 12 mo, respectively. Calculated energy and nutrient intakes were within recommended ranges and weight gain was normal. Therefore, we see no compelling reason to actively modify total fat intakes at this age. In 158 primary school children aged 6-11 y, 7-d checklist protocols showed 41% of energy intake as fat with approximately 50% as saturated fat. Because German children of this age are experiencing increasing rates of obesity and high serum cholesterol concentrations, a stepwise reduction of total fat and saturated fat intakes in primary school children appears desirable to improve long-term health.

Adult↗
PubMed2000

Bedside monitoring of cerebral blood flow in patients with acute hemispheric stroke.

OBJECTIVE: To test the practicability of a new double indicator dilution method for bedside monitoring of cerebral blood flow (CBF) and to assess the clinical value of CBF monitoring as a prognostic tool for outcome and in therapy of elevated intracranial pressure (ICP) in patients with acute hemispheric stroke. DESIGN: Prospective study. Clinical evaluation of a new method. SETTING: Neurological intensive care unit of a university hospital. PATIENTS: Ten patients with acute complete middle cerebral artery territory- or hemispheric infarctions. INTERVENTIONS: Two combined fiberoptic thermistor catheters were placed in the right jugular bulb and in the thoracic aorta. Central venous injections of ice-cold indocyanine green dye were performed. CBF was estimated by calculating the mean transit times of the cold bolus and dye. MEASUREMENTS AND MAIN RESULTS: A total of 104 reproducible CBF measurements were obtained. No complications associated with the method were observed. Twelve pairs of measurements were performed within 30 mins with unchanged clinical conditions. The standard deviation of repeated measurements was 2.7 mL/100 g/min; the interrater reliability was between 0.95 and 0.99. The median CBF in patients who died (n = 4) was lower (27 mL/100g/min) than in those who survived (n = 6) (45 mL/100g/ min). Patients who died more frequently had low CBF values of <30 mL/100g/min (22 of 38; 58%) than patients who survived (10 of 54; 19%). A total of 37 CBF measurements were done during ICP elevation of >20 mm Hg. In patients who survived, ICP elevations were only associated with low CBF values in 5 of 26 events; whereas in patients who died, ICP elevations were associated with low CBF values in 8 of 11 events. CONCLUSIONS: The new double indicator dilution technique may be suitable for serial bedside CBF measurement. It is easy to perform and can be rapidly repeated in the ICU environment. Validation of the method by comparison with standard methods is needed. The preliminary data indicate that bedside monitoring of CBF may give prognostic information for outcome and may guide therapy of elevated ICP in patients with malignant hemispheric infarction.

Acute Disease↗
PubMed2000

Redetermination of the crystal structures of the 'Arppe compound' Bi24O31Cl10 and the isomorphous Bi24O31Br10

The crystal structures of Bi24O31X10 (X = Cl, Br; 24-bismuth 31-oxide decachloride/-bromide) have been redetermined. The structure models obtained resemble the model described in the literature about 60 years ago, but differ from it in some details of the O substructure and in the fact that the structure for X = Cl is a twofold superstructure of the literature model. A fictional mechanism is given by which the formerly described incorrect O substructure is transferred into the correct one.

Journal Article↗
PubMed2000

Middle cerebral artery (MCA) susceptibility sign at susceptibility-based perfusion MR imaging: clinical importance and comparison with hyperdense MCA sign at CT.

PURPOSE: To describe the radiologic findings of susceptibility changes in acute middle cerebral artery (MCA) thromboembolism detected with three-dimensional (3D) susceptibility-based perfusion magnetic resonance (MR) imaging and to compare the detectability and clinical value of this sign with those of the hyperdense MCA sign at computed tomography (CT). MATERIALS AND METHODS: Twenty-three patients (mean age, 55 years) underwent CT and MR imaging within the first 6 hours after the onset of acute MCA stroke. The hyperdense MCA sign at CT and the presence of susceptibility changes in acute thromboembolism as depicted on T2*-weighted 3D perfusion MR images were assessed. The presence of each sign was correlated with clinical presentation. RESULTS: The sensitivity of the hyperdense MCA sign at CT was 54% (negative predictive value, 71%) compared with 82% (negative predictive value, 86%) for the susceptibility changes at MR imaging. There were no false-positive CT or MR readings. The presence of the MCA susceptibility sign correlated positively with the initial clinical presentation (chi(2) = 7.987, P =.009, Spearman rho = 0.589). However, neither of the signs was a predictor for clinical outcome in cases of spontaneous MCA stroke. CONCLUSION: In addition to the information traditionally provided with reconstructed perfusion parameter maps, 3D susceptibility-based perfusion MR images allow the identification of acute MCA thromboembolism with a sensitivity higher than that of CT.

Acute Disease↗
PubMed2000

Estrogen receptor beta (ERbeta) messenger ribonucleic acid (mRNA) expression within the human forebrain: distinct distribution pattern to ERalpha mRNA.

Estrogen has been shown to influence several brain functions as well as the expression of neuropsychiatric diseases. To date, two estrogen receptor (ER) subtypes have been identified, ERalpha and ERbeta. ERalpha messenger ribonucleic acid (mRNA) distribution in the human forebrain was recently characterized, and the highest expression was found in restricted areas of the amygdala and hypothalamus. However, no information exists with regard to ERbeta mRNA distribution in the human brain. To this end, the anatomical distribution pattern of ERbeta mRNA expression in the human forebrain was investigated in the present study. Overall, the ERbeta mRNA hybridization signal was relatively low, but the most abundant ERbeta mRNA areas were the hippocampal formation (primarily the subiculum), claustrum, and cerebral cortex; expression was also present in the subthalamic nucleus and thalamus (ventral lateral nucleus). In contrast to ERalpha (studied on adjacent brain sections), ERbeta mRNA expression was low in the hypothalamus and amygdala. Based on the revealed anatomical distribution of the human ERbeta gene expression, a putative role for ERbeta in the modulation of cognition, memory, and motor functions is suggested.

Adolescent↗