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Biomedical subjects

B Eckert

Publications and source records attributed to B Eckert.

At least 19 recordsLinked to original sources
PubMed1996

Restitution of neurophysiological functions, performance, and subjective symptoms after moderate insulin-induced hypoglycaemia in non-diabetic men.

The restoration of cognitive function was studied in 10 healthy men aged 26 years (25.5 +/- 1.2 years; mean +/- SD) after insulin-induced hypoglycaemia (arterialized blood glucose 2.5 +/- 0.4 mmol l-1) for 62 +/- 8 min. Another group of six men participated in a single blind sham study for comparison. The hypoglycaemic event caused a significant increase (p = 0.006) in serum adrenaline levels. Ratings of adrenergically mediated symptoms increased during hypoglycaemia (p = 0.006), as did neuroglycopenic symptoms (p = 0.002), although neuroglycopenia ratings increased in both studies. During hypoglycaemia, P300 amplitudes in a relatively demanding visual search task decreased (p = 0.02), whereas easier tasks were unaffected. The amplitudes were restored after 40 min of normoglycaemia. Reaction time deteriorated after restoration of normoglycaemia, suggesting an effect of hypoglycaemia on learning. Thus, hypoglycaemia at a blood glucose level that is common among patients treated with insulin causes clear cognitive dysfunction, although restoration of the cognitive dysfunction to normal was fast.

Adult↗
PubMed1996

Isolated symptomatic stenosis of the middle cerebral artery in younger adults. A clinical and ultrasonic follow-up study of eight patients.

We studied 8 symptomatic patients aged 32-56 years with isolated stenosis of the middle cerebral artery who had TIAs or minor strokes. Angiography showed MCA stenosis in the M1 segment in 7 patients, and proximal M1 occlusion that later recanalized with persistent stenosis in 1 patient, without evidence of more widespread atherosclerotic disease. A potential cardiac source of embolism was detected in only 2 patients with mitral valve prolapse. During follow-up for 39-82 months, no further ischemic events occurred, and transcranial Doppler showed unchanged or decreased stenosis in 6 patients. We conclude that isolated MCA stenosis in younger patients may be a unique pathologic entity with a benign long-term course, although previous embolism with partial recanalization appears possible in some patients.

Adult↗
PubMed1996

Calcium-mobilizing insulin secretagogues stimulate transcription that is directed by the cyclic adenosine 3',5'-monophosphate/calcium response element in a pancreatic islet beta-cell line.

In pancreatic beta-cells, calcium is required for insulin secretion, but can also stimulate gene transcription. High potassium-induced membrane depolarization and calcium influx have previously been shown to activate kinases that phosphorylate and thereby activate the transcription factor cAMP response element (CRE-binding protein (CREB) binding to CREs. It is unknown, however, whether hormones and neurotransmitters can activate this mechanism. Arginine vasopressin (AVP), bombesin, and acetylcholine potentiate glucose-induced insulin secretion and are known to raise cytosolic calcium levels through binding to cell surface receptors that activate phospholipase C. The effect of AVP on CRE-directed transcription was examined in the beta-cell line HIT. AVP (0.1-100 nM) stimulated gene transcription after transient transfection of a reporter gene that was placed under the transcriptional control of a CRE. This effect was inhibited by a vasopressin V1 receptor antagonist and depended on calcium influx and calcineurin phosphatase activity. By immunoblots with antiphospho-CREB antibodies and by using a Gal4-CREB fusion protein, it was shown that AVP induces the phosphorylation and activation of CREB. Like AVP, bombesin (100 nM) and the muscarinic agonist carbachol (200 microM) stimulated CRE-mediated transcription. These results show that calcium-mediating insulin secretagogues can activate CREB/CRE-directed transcription in HIT cells, offering a mechanism by which these secretagogues could produce long term effects on beta-cell function, changing the pattern of gene expression.

Animals↗
PubMed1995

Loss of alleles in brain tumours: distribution and correlations with clinical course.

Gliomas (n = 44) and meningiomas (n = 24) of different grades of malignancy were analysed for allele losses at loci on chromosomes 10, 13, 17 and 22. Deletions of genetic material on these chromosomes occurred in gliomas without being restricted to any histological entity. The frequency of chromosome-10-specific allele losses increased significantly with the age of the patients and with the grade of malignancy of the tumours. Deletions of chromosome 10 material were associated with a poor prognosis. The glioblastomas of patients aged over 70 years lacked the loss of the entire chromosome 10, even in tumours with EGFR gene amplification. Deletions at loci of chromosomes 13, 17 and 22 were observed in 18-32% of all gliomas, independent of grade of malignancy, patients' age, EGFR gene amplification and clinical course. Only chromosome-22-specific allele losses were found preferentially in gliomas of female patients. Loss of chromosome 22 alleles in 44% was the only mutation detected in meningiomas. This occurred independently of grade of malignancy and biological factors.

Adolescent↗
PubMed1995

The cerebral vascular response to a rapid decrease in blood glucose to values above normal in poorly controlled type 1 (insulin-dependent) diabetes mellitus.

The effect of rapid lowering of blood glucose on cerebral blood flow (CBF) was studied in 10 Type 1 (insulin-dependent) diabetic patients (age 23.5 +/- 3.8 years; mean +/- S.D.) with longstanding, poor metabolic control (HbAlc 11.2 +/- 1.0%; normal value 4.0-5.3%) using an intravenous xenon 133 single photon emission computed tomography technique. After a fall in blood glucose, during 81 +/- 11 min (mean +/- S.E.M.), from 18.2 +/- 1.4 mmol/l to 9.2 +/- 0.9 mmol/l CBF was unchanged, but increased from its initial value of 48.8 +/- 2.9 ml/100 g per min to 57.1 +/- 2.4 ml/100 g per min (P < 0.001) when the blood glucose level was restored. The CBF was higher in the right compared to the left hemisphere at all measurements (1.8 +/- 0.5 ml/100 g per min, P < 0.01; 1.9 +/- 0.5 ml/100 g per min, P < 0.05; 2.1 +/- 0.7 ml/100 g per min, P < 0.05, respectively). The change in CBF was inversely correlated with time for fall of blood glucose, but there was no correlation with absolute levels of blood glucose. The respiratory end-tidal PCO2 decreased during the low blood glucose level, but there was no correlation between the PCO2 and CBF. The cerebral volume was unchanged during the study. The results indicate that in patients with chronic hyperglycemia a rapid fall in blood glucose may cause a rise in CBF of the same magnitude as previously shown during absolute hypoglycemia in patients with well controlled diabetes mellitus and in normal subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Distinct properties of the cAMP-responsive element of the rat insulin I gene.

The cAMP response element (CRE)-binding transcription factor CREB can mediate induction of gene transcription in response to calcium as well as to cAMP. Since the rat insulin I gene 5'-flanking region contains a CRE with an octamer-like motif (TGACGTCC), CREB binding and cAMP/calcium responsiveness of the insulin CRE were investigated. In an electrophoretic mobility shift assay and in Southwestern blot experiments, bacterially expressed recombinant CREB bound to the insulin CRE as it did to the rat glucagon and rat somatostatin gene CREs. However, in nuclear extracts of the pancreatic islet cell line HIT, protein complexes binding to the insulin CRE did not contain proteins with CREB-like immunoreactivity, although these bound to the glucagon and somatostatin CREs. When reporter fusion genes were transfected into HIT cells, the isolated insulin CRE increased basal activity and mediated transcriptional activation by cAMP. However, cAMP stimulation of transcription through the insulin CRE was weak when compared with the response through the glucagon and somatostatin CREs. Furthermore, the insulin CRE did not confer responsiveness to membrane depolarization and calcium influx, in contrast to the glucagon and somatostatin CREs. These results demonstrate that the functional properties of the rat insulin I gene CRE are different from those of the rat glucagon and somatostatin CREs which may be explained by a distinct pattern of nuclear protein binding and suggest the existence of post-translational mechanisms that decrease the binding of cellular CREB to the insulin CRE.

Animals↗
PubMed1994

Analysis of 20 primarily surgically treated chiasmatic/hypothalamic pilocytic astrocytomas.

The authors review the therapeutic results of 20 patients (aged 12 months to 30 years, mean age 9 years) with benign pilocytic astrocytoma of the chiasmatic/hypothalamic region, seen at the University Hospital Hamburg-Eppendorf between February 1980 and April 1993. Six patients suffered from neurofibromatosis 1 (NF-1). The patients were divided into two subgroups relative to tumour extension and growth patterns, as revealed by CT scans and/or MR imaging. Fourteen patients revealed a large globular suprasellar tumour extending into the hypothalamus and/or the anterior third ventricle (group A). A suprasellar tumour with optic tract involvement could be identified in six cases (group B). Subtotal (70-90%) resection was achieved in ten tumours (50%), the majority of which were of the large globular type. There were no deaths. Postoperative morbidity was comprised of visual and endocrine impairment in four patients and right hemiparesis and dysphasia in one patient. Radiation therapy was given in nine cases (45%). Three tumours (38%) were reduced in size by irradiation. Tumour progression was seen in seven patients (35%). The presence of young age and NF-1 were predictors of progressive disease in our series. Growth capacity was not related to the extent of cytoreductive surgery.

Adolescent↗
PubMed1994

Detection of MCA embolization during transcranial Doppler monitoring.

Continuous transcranial Doppler ultrasound (TCD) monitoring of the middle cerebral artery (ACM) is a potent new technique in detecting thromboembolic and haemodynamic complications in interventional neuroradiology. An illustrative case is reported of a 6-year-old boy suffering from right-sided rhabdomyosarcoma of the neck in which permanent balloon occlusion of the right ACI was attempted. During the procedure, repeated severe thromboembolic events with temporary occlusion of the M1 segment of the ACM could be detected by TCD monitoring. Complications could then be avoided by cessation of the undertaking and lysis therapy with urokinase. The report concludes that TCD monitoring during endovascular treatment provides important insight into the thromboembolic pathophysiology, guides management strategies, helps in the avoidance of devastating events and should be performed during all interventional procedures, as well as during balloon occlusion of the ACI.

Cerebral Arterial Diseases↗
PubMed1993

[The importance of PaO2 and PaCO2 values in the perioperative care of geriatric patients].

Because of the generally accepted operability of patients without any age limit nowadays, more information is needed about functional disorders of organs, for example of the lung in old age. The preoperative PaO2 value at rest in 120 patients due to undergo urological operations (average age 77.7 +/- 4.6 years) was determined as 81.81 +/- 8.63 mmHg. The PaO2 values corresponding to age were significantly higher than the reference values in literature. During cholecystectomy the respiratory volume per minute at an FECO2 of 4.5 vol.% was measured as 6.6 +/- 1.41 l/min in 54 patients with an average age of 68.7 +/- 5.8 years. There was no correlation with any anthropometrical data. Considerable fluctuations in the respiratory volume per minute make the measure of FECO2 and PaCO2 necessary. In old age the cerebral blood flow rate depends on PaCO2, so that a normocapnia is of particular importance. Similar results were found in 20 traumatologic patients aged over 80, i.e. there were considerable differences between tabular values and capnometrically controlled respiratory volume per minute. The blood gas values were measured in 50 patients over 65 years old in the immediate postoperative phase of cholecystectomy. Compared with initial values, there was a significant decrease in PaO2 at 5, 15 and 25 minutes after the operation with values at 8.22 +/- 1.83 kPa, 8.24 +/- 1.83 kPa and 8.15 +/- 1.75 kPa. These values were 27% under the preoperative values. No clinically discernible hypoxia occurred. The results support the demand that geriatric patients be given suitable attention and adequate monitoring to avoid complications due to the restricted compensationability of the organs and lungs.

Aged↗
PubMed1992

Plasma elastin-derived peptide levels in normal adults, children, and emphysematous subjects. Physiologic and computed tomographic scan correlates.

Pulmonary emphysema is likely to be the result of elastic tissue digestion by unrestrained elastase activity in the lung. Elastin breakdown by elastases results in the release of soluble elastin fragments (EDP), which may be measured in plasma by an ELISA. Plasma EDP levels measured using an ELISA were determined in the following groups: disease-free children (n = 24), 0.162 +/- 0.082 ng/ml; disease-free adult nonsmokers (n = 114), 1.74 +/- 0.8 ng/ml; smokers (n = 68), 2.76 +/- 4.59 ng/ml; reformed smokers (n = 43), 1.91 +/- 1.14 ng/ml. Adults with established pulmonary emphysema (n = 50), as defined by bullous formation on the chest radiograph, had levels of 50.83 +/- 24.8 ng/ml, significantly higher than the disease-free groups at p < 0.01. Pulmonary emphysema can be reflected by pulmonary function tests, especially those that measure the pulmonary elastic properties, and by computed tomographic (CT) scan percent emphysema score. We therefore examined the relationship of plasma EDP to these other indicators of pulmonary emphysema in a separate group of 26 subjects using elastic recoil measurements (K), and a further group of 30 subjects with CT scan percent emphysema score. A significant correlation of p < 0.001 was shown for plasma EDP and K and a significant correlation of p < 0.01 was shown for plasma EDP and CT scan percent emphysema score, these correlations suggesting that plasma EDP levels are indicators of the loss of pulmonary distensibility and of mild to moderate pulmonary emphysema. These findings suggest that pulmonary emphysema is characterized by active elastin breakdown.

Adult↗
PubMed1992

Growth hormone levels in the basal state and after thyrotropin-releasing hormone stimulation in young type 1 (insulin-dependent) diabetic patients with severe retinopathy.

Sixteen young patients with type 1 diabetes mellitus and rapidly progressive severe retinopathy were examined regarding serum levels of growth hormone before and after the i.v. administration of 200 micrograms thyrotropin-releasing hormone (TRH). Serum IGF I, HbA1c, blood pressure, urinary albumin, and serum creatinine levels were also measured. The control group consisted of type 1 diabetic patients matched for age, duration of diabetes and metabolic control with no or minimal background retinopathy. The results show that basal growth hormone levels were above normal in both groups, and that there was a paradoxical increment in growth hormone levels after TRH stimulation (p < 0.05) in patients with severe retinopathy, but the values did not differ from patients with background retinopathy. IGD I levels were normal in all patients but one, and no differences were seen between the two groups. HbA1c, serum creatine, blood pressure, and urinary albumin levels were similar in the groups but patients with severe retinopathy were treated with more insulin (p < 0.001). Thus, neither abnormal growth hormone levels, nor IGF I, seems to be associated with the development of severe retinopathy in young type 1 diabetic patients.

Adult↗
PubMed1990

The importance of multiple endocrine neoplasia syndromes in differential diagnosis.

In the differential diagnosis of endocrine symptoms, the autosomal dominant multiple endocrine neoplasia (MEN) syndromes are rare but important. We found seven index cases of MEN-I in 176 patients with adenomas of the anterior pituitary and 26 patients with primary hyperparathyroidism. Of 23 cases of medullary thyroid carcinoma and eight cases of pheochromocytoma, 14 patients are classified as MEN-IIa and one as MEN-IIb. Family screening identified six MEN-I and seven MEN-II cases among 32 individuals examined. Because of autosomal dominant inheritance and sometimes-delayed manifestation of the complete syndrome, screening of healthy and affected family members should be repeated at least every other year.

Adrenal Gland Neoplasms↗
PubMed1990

Low dose acetylsalicylic acid and thromboxane release at the site of plug formation in vivo in elderly patients with cardiovascular disease.

Thromboxane B2 (TXB2) levels in bleeding time blood and in serum were measured in 13 elderly patients with cardiovascular disease, seven of whom were receiving continuous treatment with low dose acetylsalicylic acid (ASA, 125 mg every second day--250 mg daily) for prevention of stroke. Blood sampling was performed openly, but assays of TXB2 were performed by a blinded investigator. In patients treated with ASA, median serum TXB2-levels were 4% and TXB2-levels in bleeding-time blood were less than 16% of the corresponding levels in patients without ASA (P less than 0.01). The results show that in elderly atherosclerotic patients very low doses of ASA substantially suppress TXB2 formation, not only in serum but also at the site of local haemostasis. The extent of suppression is comparable to that previously reported from young healthy subjects.

Aged↗
PubMed1990

[Several methods for determining total titers of free alpha-amino acids in body fluids].

Comparisons were made among different variants of ninhydrin reaction to determine overall titres of free alpha amino acids in body fluids. Included were para-benzoquinone, 2,4,6-trinitrobenzene sulphonic acid, and 2,4-dinitro-1-fluorobenzene (DNFB). The best reproducibility of results was recorded from DNFB which can be used, as well, for analysis of milk or rumen juice.

Amino Acids↗
PubMed1989

Topology of the transposon Tn10-encoded tetracycline resistance protein within the inner membrane of Escherichia coli.

The transposon Tn10-encoded tetracycline resistance protein TetA is an integral membrane protein responsible for the export of tetracycline from the cytoplasmic to the periplasmic side of the inner membrane of Gram-negative bacteria. From a plot of the average hydrophobicity along the sequence of this protein, a two-dimensional membrane topology with 12 transmembrane domains may be predicted. Using plasmid-bearing Escherichia coli maxicells we specifically radiolabeled the TetA protein. The amino terminus of this membrane protein was shown not to be processed, and its location on the inner side of the cytoplasmic membrane was demonstrated by a newly developed use of a chemical method. Spheroplasts and inside-out vesicles of the TetA protein synthesizing maxicells were subjected to limited digestion by proteases of different specificities. The TetA protein was not accessible to proteases from the periplasmic side. On the inner side of the cytoplasmic membrane, the carboxyl terminus and four sites accessible to endoproteases could be identified. The cleavage sites are proposed to be localized between amino acid residues 60-70, 110-130, 180-200, and at amino acid 327. These results allow the definition of a model for the two-dimensional topology of the TetA protein.

Amino Acid Sequence↗
PubMed1989

Overproduction of transposon Tn10-encoded tetracycline resistance protein results in cell death and loss of membrane potential.

High-level expression of the Tn10 tetracycline resistance protein TetA in Escherichia coli caused partial collapse of the membrane potential, arrest of growth, and killing of the cells. Since alpha-methylglucoside transport was not affected, the overproduced TetA protein may cause not destruction of membrane structure but rather unrestricted translocation of protons and/or ions across the membrane.

Bacterial Proteins↗
PubMed1986

Effect of streptokinase on fibrinogen and related proteins in plasma.

We investigated the effect of streptokinase on determination of fibrinogen and related clottable proteins in an effort to assess the relative reliability of these determinations in monitoring patients being treated with streptokinase. Citrated plasma was incubated with and without streptokinase, then assayed for fibrinogen (I), fibrin(ogen) degradation products (II), total clottable protein (III), and plasminogen (IV). Values for I decreased rapidly. Values for III and IV generally paralleled those for I, values for III lacked adequate sensitivity. II, low initially, increased to 80 mg/L in 1-2 h. Soybean trypsin inhibitor effectively stabilized all these constituents (except IV) in streptokinase-treated plasma, and we recommend that this (or some other such) inhibitor of fibrinolysis be used routinely when specimens are collected for these determinations. Data are presented that suggest that transient polymers are formed, the clinical significance of which is not known.

Blood Coagulation Tests↗