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Biomedical subjects

D Petersen

Publications and source records attributed to D Petersen.

At least 19 recordsLinked to original sources
PubMed1992

MR imaging of experimental meningeal melanomatosis in nude rats.

MR imaging of the rat brain has become an increasingly frequently used method in experimental neuroradiology. On a generally available 1.5 T whole body tomograph, supplemented with an individually made small coil and a special SE sequence we obtained fairly fine images of the structures of the rat brain. With gadolinium-DTPA, we were able to visualize posterior fossa and cervical leptomeningeal growth of intrathecally injected B16 melanoma in nude rats. Using MRI to follow experimental leptomeningeal metastasis, may provide a new means for diagnostic evaluation and preclinical testing of treatment modalities.

Animals↗
PubMed1992

Speech deficits in ischaemic cerebellar lesions.

Twelve patients with cerebellar infarction, 8 in the region supplied by the posterior inferior cerebellar artery (PICA) and 4 in the territory of the superior cerebellar artery, underwent formal perceptual examination for speech deficits. With respect to topography the results firstly underline the significance of the paravermal region of the superior cerebellar portion for speech functions. In all patients with dysarthric impairment the lesion extended to this area, whereas patients with PICA infarction sparing the superior portion of the cerebellum showed no speech deficits. Secondly the findings do not corroborate the notion of an exclusively left-sided cerebellar speech motor control, since 3 of the 4 dysarthric subjects had unilateral right-sided ischaemia. This study thirdly demonstrates that lesions of the cerebellar cortex without involvement of the dentate nucleus can cause dysarthric impairment. Phonetic analysis revealed irregularly distributed articulatory deficits and slowed speech tempo as the most common dysarthric features.

Adult↗
PubMed1992

[The detailed imaging of vessels in MR angiography via projections from irregularly restricted data sets].

A new method for postprocessing of three dimensional magnetic resonance angiography data sets is described. Two operations are performed with the data set prior to maximum intensity projection. First, an irregular part of interest is marked interactively within the data set. By restricting the projection algorithm to this region, a disturbing overlay by vessels of other regions is avoided. Secondly, a three dimensional interpolation of the original data set is performed. While the spatial resolution of vessel representation is unchanged, the quality of the maximum intensity projection is improved significantly. The diagnostic value of this method is demonstrated by visualisation of a carotid aneurysm and of the deep and superficial cerebral veins.

Algorithms↗
PubMed1992

[Narrowing of the palpebral fissure as the first symptom of extensive osteoma with orbital involvement].

Unilateral narrowing of palpebral fissure and moderately impaired visual acuity induced a 14 years old woman to consult an ophthalmologist. Neuroradiological examination revealed a large osteoma starting from the ethmoid cells and invading both the orbit and the cranial cavity. This case illustrates that proptosis may be absent even in cases of extensive and compact orbital tumors. Therefore, exophthalmos is a common but not an indispensable sign of an orbital tumor. In Gardner's syndrome osteomas are associated with soft tissue tumors, intestinal polyposis and colonic adenomatosis that ultimately progresses to colorectal cancer. This association is frequent enough that a colon examination should be suggested to all patients with osteoma.

Adolescent↗
PubMed1992

Bilateral spastic cerebral palsy--pathogenetic aspects from MRI.

Thirty eight children with bilateral spastic cerebral palsy underwent MRI at the age of 5 years and more. Twenty nine showed correlates of periventricular leucomalacia, which were found especially in preterms (20 out of 21) but also in 9 of 15 fullterms without birth asphyxia. These findings suggest compromising events in the peri- and neonatal period especially in preterms and prenatal 3rd trimenon compromise in most of the fullterms without birth asphyxia.

Adolescent↗
PubMed1992

Very-late-onset adrenoleukodystrophy: possible precipitation of demyelination by cerebral contusion.

We report the clinical history, neuroradiology, and autopsy findings in a patient with very late onset, at age 57, of adrenoleukodystrophy (ALD) presenting with dementia, hemianopia, and gait apraxia. Open brain biopsy, elevated plasma very-long-chain fatty acids, and autopsy confirmed the diagnosis of ALD. Demyelinative lesions were most extensive at the site of a recent cerebral contusion. CNS trauma may have precipitated or accelerated demyelination in this patient carrying the ALD gene.

Adrenoleukodystrophy↗
PubMed1992

[Compensation in leg length inequality with orthopedic shoe measures].

There are three different methods of compensating for differences in leg length. The first is the construction of special shoes, which is adequate for differences of up to about 3 cm. The heels can be either higher or lower, or a cork sole 5-10 mm thick can be incorporated, the shaft made higher, and supplementary features, such as aids to push-off, can also be implemented. The second method is the wearing of the classic orthopedic boot or shoe, in which the necessary compensation for the shorter leg is incorporated as a part of the orthopedic footwear. The third method is the construction of a shoe within a shoe, for which different designs have crystallized out for the five groups presented. All designs incorporate leather, the tried and tested material, next to the skin. Stabilizing components are made of fiberglass-reinforced synthetic resin or Thermoplast. New materials allow aesthetically acceptable orthopedic footwear. On average, such shoes are 25% lighter than conventional orthopedic boots. The stability and wear-resistance allow large perforations and open-toe designs, which has made it possible to solve the problem of ventilation.

Artificial Limbs↗
PubMed1992

Monoclonal fluorescence polarization immunoassay evaluated for monitoring cyclosporine in whole blood after kidney, heart, and liver transplantation.

In a prospective study we evaluated a novel fluorescence polarization immunoassay (FPIA) for determining cyclosporine (CsA) in whole blood. FPIA uses a monoclonal antibody and is performed on the TDx (Abbott). The within-series (CV less than 2%) and between-days (CV less than 3.3%) precision of the assay was excellent. The results obtained by the monoclonal FPIA in samples from transplant patients (n = 100) averaged 31.9% and 20.2% higher than those by HPLC and a specific radioimmunoassay (INCStar), respectively. Results by all three methods correlated well. Follow-up studies during the early course after liver transplantation, however, suggested that high metabolite concentrations affect FPIA results. This is explained by previously described cross-reactions of the monoclonal antibody with some CsA metabolites. The FPIA results in samples of such patients should be interpreted cautiously.

Chromatography, High Pressure Liquid↗
PubMed1991

Multiple-dose pharmacokinetics of epirubicin at four different dose levels: studies in patients with metastatic breast cancer.

Pharmacokinetic analysis of epirubicin and its metabolites epirubicinol and 7-deoxy-13-dihydro-epirubicinol aglycone during the first and the fourth courses of treatment was performed in 78 patients with metastatic breast cancer. The patients were treated every 3 weeks with epirubicin given as 10-min i.v. infusions at four different dose levels: 40, 60, 90 and 135 mg/m2. In most cases (76 of 78 cases), plasma concentration-time curves fitted to a three-compartmental pharmacokinetic model. The terminal half-life of epirubicin was independent of dose and duration of treatment. Large interindividual differences were demonstrated (mean t1/2 gamma, 21.6 +/- 7.9 h; range, 10.6-69 h; n = 110). In two subjects, extremely long half-lives and high serum bilirubin concentrations indicated impaired liver function. No correlation was found between the half-life and levels of liver alanine aminotransferase (ALAT) or serum creatinine. The metabolite epirubicinol appeared quickly after epirubicin administration and its half-lives were shorter than that of the parent compound (mean t1/2 gamma, 18.1 +/- 4.8 h; range, 8.2-38.4 h; n = 105). Formation of the aglycone metabolite was delayed and the half-life of this metabolite was shorter than that of epirubicin (mean t1/2 gamma, 13 +/- 4.6 h; range, 2.7-29 h; n = 104). The AUC of epirubicin and the total AUC (drug and metabolites) were linearly proportional to the dose, with the former value constituting two-thirds of the latter. A correlation was found between AUC and the plasma concentration of epirubicin at two time points (2 and 24 h after administration). The proposed model was AUC = 9.44 x c2 + 62.5 x c24 + 157.7 (r = 0.953).

Breast Neoplasms↗
PubMed1991

A randomized study of epirubicin at four different dose levels in advanced breast cancer. Feasibility of myelotoxicity prediction through single blood-sample measurement.

Detailed pharmacokinetic analysis and subsequent evaluation of myelotoxicity were performed in 55 patients who had been randomized to 4 different doses of epirubicin (40, 60, 90 or 135 mg/m2 given i.v. every 3 weeks). A significantly positive correlation was demonstrated between the AUC and the myelotoxicity of epirubicin. A similar correlation was observed when the metabolite epirubicinol was also considered. The decrease in leucocyte count as expressed by the logarithmic ratio between nadir WBC and initial WBC was linearly correlated with the AUC of either epirubicin alone (r = -0.55, P less than 0.001) or epirubicin and epirubicinol together (r = -0.63, P less than 0.001). As a relationship between the concentration of epirubicin in a single plasma sample taken at 6 h following i.v. administration and the AUC of the drug has been established, a log-linear relationship between the expected decrease in leucocytes and the concentration at 6 h after administration could be calculated. The proposed model is expressed as the equation: log WBCnadir = log WBCinitial -0.0073 x c6 (ng/ml)-0.14.

Bone Marrow↗
PubMed1991

Superficial siderosis of the central nervous system. A 37-year follow-up of a case and review of the literature.

The course of a patient suffering from superficial siderosis of the central nervous system for 37 years is presented and diagnostic and therapeutic approaches are evaluated. The syndrome is clinically defined by slowly progressing deafness, cerebellar ataxia, myelopathy and neuropsychological deficits in combination with recurrent xanthochromia of the cerebrospinal fluid with siderophages. The diagnosis may be confirmed by computed tomography, which shows degeneration of the cerebellar vermis, and by magnetic resonance imaging, demonstrating iron deposits on the surface of brain, brain stem and spinal cord. Therapy should seek to identify and remove the source of bleeding, since pharmacotherapy with iron-depleting drugs is of limited effectiveness.

Brain Diseases↗
PubMed1991

Neurosarcoidosis without systemic sarcoidosis.

Neurosarcoidosis is a well-recognised complication of systemic sarcoidosis but diagnosis may be difficult if there is no clear evidence of an extracerebral manifestation of the disease. We present the case of a 42-year-old woman with clinical features characteristic of cerebral sarcoidosis including tetraparesis, diabetes insipidus, diencephalic hyperphagia, personality changes, and memory loss. Diagnosis was supported by cerebrospinal fluid (CSF) findings and magnetic resonance imaging (MRI): CSF showed mild lymphocytic pleocytosis, intrathecal production of IgG without oligoclonal bands, and a raised level of lysozyme. MRI revealed multiple contrast-enhanced granulomas at the base of the brain with partial involvement of diencephalic and mesencephalic structures and parts of the spinal cord. There was no evidence of systemic manifestation of sarcoidosis. Administration of corticosteroids led to improvement of the symptoms.

Adult↗
PubMed1991

A wooden foreign body penetrating the superior orbital fissure.

The case of a 12-year-old patient with a wooden foreign body which had penetrated the superior orbital fissure is presented. Using a transethmoidal approach, only some splinters lying in the periorbital soft tissue were removed. The patient became febrile, indicating an infectious complication due to a retained foreign body. This was confirmed by CT scan and MRI demonstrating a main splinter in the superior orbital fissure. Total removal of the wood was achieved via a pterional extradural approach. The difficulties of identifying wooden foreign bodies as well as the topographical problems involved with the approach to the superior orbital fissure are discussed.

Bicycling↗
PubMed1991

Early onset cerebellar ataxia with retained tendon reflexes. Clinical, electrophysiological and MRI observations in comparison with Friedreich's ataxia.

Fourteen patients with the clinical diagnosis of early onset cerebellar ataxia with retained tendon reflexes (EOCA) were examined and compared with 11 patients with Friedreich's ataxia (FA). The mean age of onset in EOCA was 15.9 +/- 6.0 yrs (FA: 14.0 +/- 5.7 yrs). Annual progression rate and the percentage of patients who were wheelchair-bound was lower in EOCA as compared with FA, although the difference did not reach statistical significance. The latency until becoming wheelchair-bound, however, was significantly longer in EOCA than in FA. The segregation ratio in EOCA was significantly lower than 0.25. Clinically, EOCA and FA patients presented with a progressive cerebellar syndrome. Associated symptoms, such as muscle wasting, sensory disturbances, foot deformity, scoliosis and electrocardiographic abnormalities were encountered less frequently in EOCA than in FA patients. The electrophysiological findings in EOCA were variable and pointed to axonal degeneration in peripheral nerves and central pathways. Posturographic measurements revealed a higher incidence of anteroposterior sway direction in EOCA as compared with FA, suggesting a cerebellar type of ataxia in EOCA. Eleven out of the 14 EOCA patients had cerebellar atrophy in MRI. The characteristic MRI finding in FA was upper cervical cord shrinkage and only minor atrophy of the cerebellum. The demonstration of cerebellar atrophy in the majority of EOCA patients supports the view that EOCA is distinct from FA. It is uncertain, however, whether EOCA is a homogenous disease entity or a group of phenotypically similar syndromes.

Action Potentials↗
PubMed1990

Localized 1H in vivo NMR spectroscopy of small-volume elements in human brain at 1.5 T.

Localized in vivo proton NMR spectra of volume elements of minimal size (13 x 13 x 13 mm3) were obtained in human brain with a whole-body imager working at 1.5-T field strength. By use of an optimized version of the 90 degrees-180 degrees-180 degrees volume selection method, well-resolved proton spectra were acquired within 9 min and a comparison of spectra with different echo times (135 and 270 ms) was possible within 20 min.

Body Water↗
PubMed1990

Central pontine myelinolysis associated with low potassium levels in alcoholism.

Two patients with chronic alcohol abuse and central pontine myelinolysis are described. One developed a Korsakoff syndrome 2 days before admission to our hospital and the other showed signs of a incipient delirium without Korsakoff syndrome. Diagnosis of incipient central pontine myelinolysis was based on acute brain-stem dysfunction, serum electrolyte disturbances, malnutrition with vitamin B1 (thiamine), B6 (pyridoxine) and B12 (cyanocobalamin) deficiency in combination with typical neuroradiological findings. Hypokalaemia but no disturbance in serum sodium levels was found in both patients. After correction of hypokalaemia and vitamin deficiency the patients showed complete recovery of neurological and neuropsychological function. The findings are interpreted as suggesting that disturbances in serum potassium levels as well as rapid correction of hyponatraemia may be associated with pontine swelling and dysfunction which, if undetected, leads to central pontine myelinolysis.

Adult↗
PubMed1990

Variation of contrast between different brain tissues with an MR snapshot technique.

The lack of tissue contrast in gradient-echo sequences with very short repetition times can be overcome by using a single inversion pulse prior to the entire imaging sequence. The contrast can be changed by variation of the time delay between the inversion pulse and the first excitation. This snapshot technique was introduced for very fast acquisition of images, but it also provides images with a strong contrast of gray to white matter and of brain tissue to cerebrospinal fluid. The authors designed a sequence that allows sufficient spatial resolution and good image quality. The measurement time is 1.2 seconds, and the in-plane resolution is 0.8 mm. A large variation in contrast with different inversion times was demonstrated on brain images of volunteers and patients.

Brain↗