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Biomedical subjects

E Hofmann

Publications and source records attributed to E Hofmann.

At least 109 records · Page 6Linked to original sources
PubMed1992

Neurological long-term follow-up in left atrial myxoma: are late complications frequent or rare?

Neurological manifestations were analysed in 13 patients with left atrial myxoma confirmed by histological study. In this group, 6 patients had neurological complaints at initial presentation, 5 had cardiac symptoms, and 4 patients presented with signs of systemic disease. CT was performed in 10 and MRI in 7 patients. There were signs of ischaemic or haemorrhagic infarction (6 of 12) and one lesion suggestive of myxoma metastasis; other findings mainly comprised non-specific white matter lesions revealed by MRI. Neurological follow-up 0.5-8 years after tumour resection revealed no delayed neurological complications, follow-up CT and MRI findings were not suggestive of lesions acquired after operation. It is suggested that this rare condition of cardiac myxoma should be suspected in young patients with CNS symptoms or signs lacking cerebrovascular or cardiovascular risk factors and should be included in the differential diagnosis of vasculitis. With timely diagnosis and resection of the cardiac tumour the long-term prognosis can be considered improved.

Adult↗
PubMed1992

MRI white matter hyperintensity in neuroleptic malignant syndrome (NMS)--a clue to pathogenesis?

The case of a young female patient with neuroleptic malignant syndrome (NMS) and extended MRI white matter hyperintensity in the left parietal and both occipital lobes is reported. MRI lesions resembled findings in hypertensive encephalopathy, they were not readily compatible with CNS vasculitis. Venous sinus thrombosis could be ruled out. Vascular encephalopathy with transient white matter edema and a small residual left parietal lesion is suggested. Neurochemical implications are discussed with particular reference to a possible involvement of excitatory amino acids in NMS pathogenesis.

Adult↗
PubMed1992

Sex hormone binding and peritumoural oedema in meningiomas: is there a correlation?

Steroid receptor binding activity was evaluated in specimens of 28 human cerebral meningiomas using a dextran coated charcoal (DCC) assay. Oestrogen receptor (ER) binding activity at significant levels (greater than 10 fmol/mg protein) could be detected only in three postmenopausal females (11% positive cases) at low levels. Positive progesterone receptor (PR) binding was detected in eighteen of the twenty-eight analysed meningioma tissues (64% positive cases). A significantly higher level of PR in male than in female patients could be demonstrated. The degree of peritumoural oedema could be evaluated from CT scans. There was no significant correlation between lack and amount of peritumoural oedema and quantity of cytosolic PR binding activity. Therefore we conclude, that peritumoural oedema is related to other factors and a possible role of PR activity in development of peritumoural oedema and growth control of meningiomas could not be demonstrated.

Adult↗
PubMed1992

Overexpression of human DNA repair protein N-methylpurine-DNA glycosylase results in the increased removal of N-methylpurines in DNA without a concomitant increase in resistance to alkylating agents in Chinese hamster ovary cells.

N-Alkylpurines induced in DNA by simple monofunctional alkylating agents are known to be cytotoxic and possibly indirectly mutagenic. These adducts are removed by the ubiquitous N-methylpurine-DNA glycosylase (MPG) in a multistep repair pathway. Chinese hamster ovary (CHO) cell clones expressing 2- to 16-fold enhanced levels of MPG activity were isolated from cells stably transfected with human MPG cDNA expression plasmids. The in vivo removal of 3-methyladenine and 7-methylguanine from some of these lines was analyzed and was observed to reflect their MPG levels. These cell lines did not develop increased resistance, as compared to the control, in regards to cytotoxic, mutagenic and sister chromatid exchange inducing effects of the alkylating agents that induce 3-alkyladenine and 7-alkylguanine as the major alkyl adducts in DNA. These results suggest that the MPG activity is not limiting in the multi-step repair pathway of N-alkylpurines in CHO cells.

Alkylating Agents↗
PubMed1992

Transcranial color-coded real-time sonography in the evaluation of intracranial neoplasms and arteriovenous malformations.

Transcranial color-coded real-time sonography (TCCS) was performed in 57 patients with primary intracranial brain tumors (n = 49) or arteriovenous malformations (n = 8) to evaluate its diagnostic potential. In 46 patients (81%), lesions could be identified employing this technique. In 7 patients, transcranial ultrasound examination was not feasible because of bone thickness; in the remaining 4 patients, the tumor was indistinguishable from adjacent brain tissue despite sufficient insonation, suggesting that these neoplasms are isoechogenic. The sonographic features of brain tumors were very similar: a hyperechogenic matrix of the lesion was interspersed by hypoechogenic pixels. Larger hypoechogenic areas (0.5-1 cm) gave evidence of tumor necrosis. Differences between the findings of TCCS and computed tomography concerning tumor size were found in 7 patients, in whom TCCS revealed an area of smaller extension within the corresponding hypodense area on the computed tomographic scan. Perifocal brain edema could not be detected by ultrasound examination. In 13 patients, a thin, hypoechogenic peritumoral halo was disclosed that did not correlate with perifocal brain edema identified by computed tomography and that may have been due to compression of adjacent parenchyma. In patients with arteriovenous malformations, TCCS permitted the identification of the main feeders, the nidus, and the draining venous system by color-coded depiction of intravascular blood flow. In conclusion, TCCS is an additional method for initial diagnosis and highly suitable for follow-up in tumor patients and provides valuable information about tissue characteristics and blood flow.

Adult↗
PubMed1992

[Miliary tuberculosis as a complication of BCG immunotherapy in cancer of the bladder. Case report].

Intravesical administration of BCG may be used as an ancillary immunotherapy after endoscopic resection for cancer of the bladder. Local side effects are usually mild. Here is reported a patient who developed miliary tuberculosis after this form of therapy. Radiologic studies of the thorax and liver biopsy confirmed the diagnosis. The patient recovered after treatment with anti-tuberculosis drugs (TA-81 scheme). Epithelial trauma may be invoked as an alteration facilitating this complication. Although it develops infrequently, patients with bladder cancer treated with BCG must be monitored for this complication.

BCG Vaccine↗
PubMed1992

[Remission of schizophreniform psychosis after brain tumor surgery].

A 19-year-old female was admitted to hospital due to a schizophrenia-like psychosis of the paranoid type including delusions and various hallucinations. Neurologically she only showed tics of the eyebrows with increased eye blinking. 30 months before an astrocytoma located on the left basal temporal lobe had been resected after the patient suffered from several psychomotor and two grand mal seizures. Following post-operative anticonvulsant therapy seizures had completely disappeared and the patient had been free of symptoms of any kind. After the acute onset of the psychosis another follow-up MRI of the brain using coronary sections revealed a small relapse-tumor. Symptoms disappeared after high-dose neuroleptic therapy. Finally another surgical intervention led to a lasting remission of the psychotic symptomatology (so far 18 months). Postoperatively neuroleptics could be discontinued. Clinical picture and MRI findings will be discussed with a focus on possible etiological factors in schizophrenia.

Adult↗
PubMed1991

Do arachnoid cysts grow? A retrospective CT volumetric study.

The volumes of intracranial arachnoid cysts were measured in 136 CT scans of 86 patients. Absolute and relative cyst size was calculated. Left hemisphere and middle cranial fossa location prevailed. A slight negative correlation of relative cyst size with age (r = -0.21, NS) disappeared when analysis was restricted to the adult age group (greater than or equal to 20 years). After the sample was divided into two groups according to relative cyst size (cysts less than mean volume vs cysts greater than mean volume), small AC showed no correlation with age, while large AC correlated positively with age (r = 0.79, P less than 0.05). A subgroup of large AC appears to expand with time, while the majority of small AC remain unchanged.

Adolescent↗
PubMed1991

Solid-cystic (papillary-cystic) tumours within and outside the pancreas in men: report of two patients.

Solid-cystic (papillary-cystic) tumours (SCT) of the pancreas are distinctive neoplasms with a predilection for young female patients. This is the first detailed report describing the occurrence of SCT in two young male patients. Except for the extapancreatic occurrence of one of the tumours (in the retroperitoneal region behind the head of the pancreas), all other clinicopathological features were identical to those characterizing the SCT in women. Immunostaining was (at least focally) positive for Lu 5 (broad spectrum keratin marker), vimentin and alpha-1-antitrypsin. The tumours were negative for neuroendocrine markers (except for neuron-specific enolase), pancreatic hormones and enzymes, pancreatic stone protein, carcinoembryonic antigen, CA 19-9 and nuclear oestrogen and progesterone receptors. This report does not support the suggested female sex hormone dependence of SCT.

Adult↗
PubMed1991

Interaction of 5-azacytidine and dexamethasone in the control of hepatic tyrosine aminotransferase.

The nucleoside analog 5-azacytidine is able to induce tyrosine aminotransferase several-fold in the liver of suckling rats. Bilateral adrenalectomy abolishes this inducing effect. The drug also decreases significantly the concentration of cytosolic glucocorticoid receptor accompanied by an increase of the glucocorticoid receptor concentration in the nuclei. The antiglucocorticoid RU 486 which abolishes the induction of tyrosine aminotransferase and serine dehydratase by dexamethasone very effectively is not able to inhibit either the induction of tyrosine aminotransferase or the translocation of the glucocorticoid receptor into the nuclei by 5-azacytidine.

Animals↗
PubMed1991

Differences in the accessibility of the beta-adrenergic receptor in isolated hepatocytes from foetal and adult rats.

Beta-receptor number (measured by [3H]-CGP 12 177 binding) and beta-adrenergic response (measured by isoproterenol stimulated glucose liberation and isoproterenol stimulated adenylate cyclase activity) were compared in hepatocytes isolated from foetal (on day 22 of gestation), adult female and adult male rats. Beta-receptor numbers in crude membrane preparations of hepatocytes from adult female and adult male rats were found to be nearly equal (15.5 and 15.1 fmol/mg), but in crude membrane preparations of foetal rats beta-adrenergic receptor number was significantly higher (34.3 fmol/mg). Determination of number of beta-adrenergic surface receptors of intact hepatocytes showed relative high values in foetal rats (about 22,000/cell) and adult female rats (about 20,000/cell), but in male rats the number was less (about 6500/cell). Glucose liberation was stimulated by isoproterenol to the same extent in hepatocytes isolated from adult female and foetal rats (about 150% over basal), whereas no effect was found in hepatocytes isolated from adult male rats. Dose-response curves showed that in foetal rat hepatocytes glucose release was already increased by 10(-8) M isoproterenol, whereas in female rat hepatocytes at least 10(-6) M isoproterenol was required. Adenylate cyclase was stimulated by isoproterenol in lysates of hepatocytes from adult female rats by about 180% and from foetal rats by about 250%. No effects were observed using lysates of hepatocytes from adult male rats. We interpret the observed differences of beta-adrenergic responses between adult female and male rats as being primarily caused by different accessibility of the beta-receptor to the beta-agonist isoproterenol in intact hepatocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenylyl Cyclases↗
PubMed1991

Fructose-2,6-bisphosphate metabolism in permeabilized yeast cells.

Several methods for the permeabilization of Saccharomyces cerevisiae M1 were compared. Cells were permeabilized in the presence of 3% toluene/mercaptoethanol, and the activities of 6-phosphofructo-2-kinase, fructose-2,6-bisphosphatase and alkaline phosphatase were measured during growth of yeast on glucose. In the exponential phase of growth, the specific activities of 6-phosphofructo-2-kinase and fructose-2,6-bisphosphatase decrease significantly. The specific activities of 6-phosphofructo-2-kinase and high-affinity fructose-2,6-bisphosphatase increase again during the transition phase and reach maximum values in the stationary phase. In contrast to the specific activities, the activity concentrations of 6-phosphofructo-2-kinase and fructose-2,6-bisphosphatase remain nearly constant in the exponential phase, but increase in the transition and the stationary growth phase. The concentration of fructose-2,6-bisphosphate drops from about 6 microM in the exponential phase to very low levels in the transition phase, but increases slightly in the stationary phase. In Saccharomyces cerevisiae M1 several fructose-2,6-bisphosphate degrading activities were measured differing in the behaviour during growth on glucose, in the pH-optimum and the inhibition by fructose-6-phosphate.

Alkaline Phosphatase↗
PubMed1991

Enzyme activities, isoenzyme pattern and alpha-1-adrenergic receptor number in primary cultured hepatocytes.

Changes in the activities of pyruvate kinase, tyrosine aminotransferase and adenylate cyclase as well as in the number of alpha-1-adrenergic receptors of hepatocytes maintained in primary culture were investigated. During the culture in the presence of insulin and dexamethasone the activity of tyrosine aminotransferase (TAT) increased. The increase was suppressed by 12-O-tetradecanoylphorbol-13-acetate (TPA). The basic activity of adenylate cyclase increased; however, a weaker stimulation of the enzyme by glucagon was found. A loss of stimulation of pyruvate kinase by fructose-1,6-bisphosphate may result from phosphorylation of the enzyme. The number of alpha-1-adrenergic receptors decreased during culture, an event not influenced by TPA.

Adenylyl Cyclases↗
PubMed1991

Simple and rapid purification of F1-ATPase from bovine heart mitochondria by affinity chromatography.

A simple and rapid method for the isolation of bovine heart mitochondrial adenosine 5'-triphosphatase (F1-ATPase) was developed. Mitochondria were purified by differential centrifugation and stored frozen. After thawing. F1-ATPase was released by treatment with chloroform. Purification of the enzyme was achieved by polyethylene glycol precipitation followed by chromatography on Procion Navy H-ER beaded cellulose in the presence of MgCl2. F1-ATPase was eluted by ATP in the absence of MgCl2. The purity of the enzyme was proved by SDS-polyacrylamide-gel electrophoresis. The purified F1-ATPase showed slightly non-hyperbolic kinetics towards ATP and nearly complete inhibition in the presence of millimolar concentrations of ADP.

Adenosine Diphosphate↗
PubMed1991

Kinetics of 6-phosphofructo-1-kinase from a yeast mutant.

The steady state kinetics of 6-phosphofructo-1-kinase was determined in a cell-free extract obtained from a yeast mutant (DFY 250) and compared with the kinetic properties of the enzyme of a wild-type strain (DFY 1). 6-Phosphofructo-1-kinase from the DFY 250 strain shows a complex kinetic behaviour, which is qualitatively similar to, but quantitatively different from, that of normal yeast 6-phosphofructo-1-kinase. The mutant enzyme has a lower affinity to its activators fructose 6-phosphate, fructose 2,6-bisphosphate and AMP. The inhibiting effect of ATP on the mutant 6-phosphofructo-1-kinase is substantially weaker than on the wild-type enzyme. A complex interaction between fructose 6-phosphate and fructose 2,6-bisphosphate at the 6-phosphofructo-1-kinase from strain DFY 250 is reflected by a remarkable substrate inhibition by fructose 6-phosphate even at saturating fructose 2,6-bisphosphate. The kinetic data were fitted to different variants of the Monod-Wyman-Changeux model by nonlinear regression analysis. It turned out that the influence of fructose 6-phosphate, ATP, AMP and fructose 2,6-bisphosphate on the activity of 6-phosphofructo-1-kinase from wild-type and DFY 250 strain could be described by rate equations of essentially the same structure.

Adenosine Diphosphate↗
PubMed1991

Yeast phosphofructokinase: kinetic characterization of a substrate-imprinted enzyme conformation.

Intramolecular cross-linking of octameric yeast phosphofructokinase was applied to study the effect of substrate-imprinted conformational changes on the regulatory properties of the enzyme:Cross-linking performed in the presence of fructose 6-phosphate yields a substrate-imprinted enzyme species the affinity of which towards this substrate is significantly higher than that of native phosphofructokinase and of the enzyme cross-linked in the absence of fructose 6-phosphate. The enzyme cross-linked in the presence of fructose 6-phosphate does not exhibit cooperativity with respect to this substrate but is still activated by AMP and by fructose 2,6-bisphosphate. This activation consists in an increase of substrate affinity with respect to fructose 6-phosphate. In the absence of positive effectors, the maximum activity of the cross-linked enzyme corresponds to the respective values of native phosphofructokinase when activated by AMP or by fructose 2,6-bisphosphate. At saturating levels of AMP and of fructose 2,6-bisphosphate, nearly identical affinities with respect to fructose 6-phosphate are found, ranging between the Km values of native phosphofructokinase activated by AMP and by fructose 2,6-bisphosphate. Covalent stabilization of the substrate-imprinted enzyme conformation does not affect the interaction of phosphofructokinase with ATP at the substrate-binding site. The results suggest that the allosteric regulation of yeast phosphofructokinase is mainly related to conformational changes controlled by fructose 6-phosphate while the ATP affinity at the catalytic site of the enzyme remains essentially unaffected.

Adenosine Monophosphate↗
PubMed1991

[Intestinal Microspora infections in a patient with acquired immunodeficiency syndrome].

A 24 year old man with AIDS diagnosed in 1989 and a history of several episodes of pulmonary pneumocystosis developed chronic diarrhea and severe epigastric pain. Endoscopy revealed a granular intestinal mucosa. There was atrophy of villi and Giemsa, Ziehl-Nielsen and Gram staining identified 1.5 to 2 u spores in the cytoplasm of intestinal cells. Transmission electron microscopy of the spores revealed a thick wall, a sporoplasm with a nucleus, ribosomes, a posterior vacuole and a polar filament with multiple coils; no mitochondria were seen. Thus, the patient had intestinal microsporidiosis caused by Enterocytozoon bieneusi. This is a rare pathogen recently identified in man.

AIDS-Related Opportunistic Infections↗