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M Jensen

Publications and source records attributed to M Jensen.

174 records · Page 10Linked to original sources
PubMedDate not supplied

Three-dimensional MR imaging and display of intracranial disease: improvements with the MP-RAGE sequence and gadolinium.

Three-dimensional (3D) image rendering was performed in 14 patients who had undergone magnetic resonance (MR) imaging for focal brain lesions. The MR study included the magnetization-prepared rapid gradient-echo (MP-RAGE) sequence with 64 or 128 partitions. Resultant contiguous sections 2.5 or 1.25 mm thick, respectively, were obtained. Images were acquired before and after administration of gadopentetate dimeglumine. Resultant 3D data sets were processed on a commercially available workstation. Correlative surgical observation was performed in four cases. All data sets were successfully processed into 3D images. The precontrast images proved superior to gadolinium-enhanced images for brain surface rendering. Postcontrast images proved superior for reconstruction of tumors and vascular structures. The 64-partition data set proved sufficient for all postprocessing. Coronal orientation was preferred to sagittal orientation for surface rendering because it provided optimal orthogonal orientation of sulcal and gyral brain surface features. Three-dimensional rendition allowed easy superposition of lesion, brain, vessels, and scalp features--all useful for surgical planning. The central sulcus was easily recognized in the midline partitions and traced mediolaterally for projection on the cortical surface. MP-RAGE provides a 3D data set that can be obtained in just over 3 minutes, from which clinically useful 3D renderings are possible. The rapidity of acquisition and capability for 3D rendering provides additional clinical utility.

Adolescent↗
PubMedDate not supplied

Rapid tumor lysis in a patient with B-cell chronic lymphocytic leukemia and lymphocytosis treated with an anti-CD20 monoclonal antibody (IDEC-C2B8, rituximab).

In this report we present a patient with B-cell chronic lymphocytic leukemia who developed an acute tumor lysis syndrome after administration of the human anti-CD20 antibody IDEC-C2B8 (RITUXIMAB) in standard dose of 375 mg/m2. IDEC-C2B8 has been demonstrated to have only mild and tolerable side effects in patients with follicular lymphoma. In these trials patients with lymphocytosis >5000/microl were excluded. Physicians must be aware of this hitherto unreported phenomenon in patients with high CD20-positive blood counts.

Adult↗
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Deficiency in complex IV (cytochrome c oxidase) of the respiratory chain, presenting as a leukodystrophy in two siblings with Leigh syndrome.

Two siblings with Leigh syndrome presenting at the age of 6 months with clinical and radiological features suggestive of a leukodystrophy are reported. A deficiency in complex IV of the respiratory chain (cytochrome c oxidase) was demonstrated in muscle mitochondria of both patients. To our knowledge, this is the first familial case of Leigh syndrome due to cytochrome c oxidase deficiency, presenting clinically and radiologically with signs of a leukodystrophic process. We suggest that respiratory chain enzyme defects should be considered in the differential diagnosis of cases suggestive of a leukodystrophy.

Brain↗
PubMedDate not supplied

Sources of amino acids for protein synthesis during early organogenesis in the rat. I. Relative contributions of free amino acids and of proteins.

Rat conceptuses on the 10th day of gestation were cultured for 27 h in whole rat serum. An addition of either [3H]leucine or [3H]leucine-labelled rat serum proteins was made once during the culture period, and the acid-soluble and acid-insoluble radioactivities of embryo and visceral yolk sac measured at harvesting. The extent of radiolabel incorporation into embryonic and yolk-sac proteins increased linearly with the duration of exposure of the conceptus to the radiolabelled leucine or radiolabelled serum proteins, indicating roughly constant rates of incorporation, per unit mass of tissue, throughout the culture period. The incorporation rates, expressed as clearances, were 0.73 and 0.78 microliter/mg tissue protein/h for embryo and yolk sac, respectively, when the source was [3H]leucine; and 1.8 and 1.3 microliters/mg tissue protein/h, for embryo and yolk sac, respectively, when the source was [3H]leucine-labelled serum proteins. It is estimated, from the known leucine and protein concentrations in serum, that protein contributed over 99 per cent of the leucine supplied to the conceptus for its protein synthesis. In parallel experiments, measurements were made on cultures conducted in the presence of an antiserum against rat visceral yolk sac (100 micrograms/ml). Antiserum profoundly inhibited incorporation of radioactivity into embryo and yolk-sac proteins, when the source was 3H-labelled protein, a result consistent with the known ability of the antiserum to inhibit pinocytosis in the yolk sac. Antiserum also decreased incorporation from [3H]leucine in the yolk sac, suggesting that a proportion of the free leucine entering the yolk sac does so by pinocytosis. The failure of antiserum to affect incorporation of [3H]leucine into the embryo probably indicates that leucine can enter the embryo without the mediation of yolk-sac pinocytosis. The primacy of protein, as a source of amino acids for the organogenesis-stage embryo, is consistent with the serious effects, in terms of embryonic death and malformation, that result from the interruption of amino acid supply when either pinocytosis or lysosomal proteolysis in the yolk sac is inhibited.

Amino Acids↗
PubMedDate not supplied

Regional myocardial oxygen consumption estimated by carbon-11 acetate and positron emission tomography before and after repetitive ischemia.

BACKGROUND: Preserved myocardial oxygen consumption estimated by carbon 11-acetate and positron emission tomography (PET) in myocardial regions with chronic but reversibly depressed contractile function in patients with ischemic heart disease have been suggested to be caused by repeated short episodes of acute myocardial ischemia. To evaluate this hypothesis myocardial 11C-acetate PET imaging was performed before and after acute repetitive myocardial ischemia. METHODS AND RESULTS: In open chest dogs (n = 8), the left anterior descending coronary artery was occluded 4 times for 5 minutes alternating with 5 minutes of reperfusion. Before and after repetitive coronary occlusions, oxygen 15 water/oxygen 15 carbon monoxide (blood flow), and 11C-acetate (oxygen consumption) PET imaging were performed. Left ventricular regional systolic wall thickening was measured with sonomicrometry. Forty-five minutes after the ischemic episodes, systolic ventricular wall thickening was decreased by 90%, whereas myocardial blood flow was reduced by 21% compared with baseline values (P < .05). Ninety minutes after the ischemic episodes, estimated oxygen consumption was unaltered compared with the baseline level despite a sustained 70% decrease in the regional contractile function (P < .05). CONCLUSIONS: Oxygen consumption estimated by 11C-acetate PET imaging is preserved after repeated episodes of acute myocardial ischemia despite a severe impairment of contractile function.

Acetates↗
PubMedDate not supplied

The yellow variegated mutant of Arabidopsis is plastid autonomous and delayed in chloroplast biogenesis.

The yellow variegated mutant of Arabidopsis thaliana is characterized by bright-yellow true leaves that turn green- and white-sectored as leaf development proceeds. Variegation is due to the action of a nuclear recessive gene. Whereas cells in the green sectors contain morphologically normal chloroplasts, cells in the yellow and white sectors are heteroplastidic and contain plastids with rudimentary lamellar structures, as well as some normal-appearing chloroplasts. This indicates that plastids in yellow variegated are affected differently by the nuclear mutation (the mutant is "plastid autonomous"). Genetic analyses have revealed that yellow variegated is an allele of the var2 locus, and that defective plastids are not maternally inherited. The traits of plastid autonomy and lack of maternal inheritance of the plastid defect set var2 apart from other nuclear gene-induced variegations and define a novel class of variegation mutant. The primary lesion in var2 probably does not involve a blockage in the pathways of pigment biosynthesis. Under high temperatures or low light conditions, plant growth is retarded and mutant plants are nearly all-green. Considered together, our data suggest that var2 is delayed in chloroplast biogenesis. We suggest that the stochastic pattern of variegation in the mutant may be due to an interplay of factors that regulate var2 gene expression and factors that mediate rates of cell and plastid division. Plastids with a critical threshold of the partially functional var2 protein are green, while plastids containing less than the threshold of var2 activity are white.

Alleles↗
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Education, Nursing, Baccalaureate↗
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Cerebrospinal fluid tau levels increase with age in healthy individuals.

Cerebrospinal fluid (CSF) tau is a promising biochemical ante-mortem marker for Alzheimer's disease (AD). Levels are increased in AD compared to other dementias, neurological diseases and healthy controls. An age-related decrease in both soluble tau and tau bound to paired helical filaments has been shown in brains from non-demented subjects. To study tau levels in normal ageing, we investigated CSF in 29 healthy individuals aged 45-80 years. A statistically significant increase in CSF tau with increasing age was found which might be caused by neuronal loss during normal ageing and redistribution of soluble tau from the brain into CSF. We could not demonstrate any influence by the APOE genotype, though larger populations have to be investigated to confirm this result. In conclusion, we found an age-dependent increase in CSF tau in healthy individuals. We emphasise the importance of establishing an age-dependent interval of CSF tau in non-demented subjects.

Aged↗
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Activation of resting T cells against the CA 72-4 tumor antigen with an anti-CD3/CA 72-4 bispecific antibody in combination with a costimulatory anti-CD28 antibody.

The poor prognosis of advanced gastric carcinoma requires new therapeutic approaches. Among these, the specific activation of resting lymphocytes by bispecific antibodies may be promising. Here we describe the generation and function of a bispecific monoclonal antibody (bi-mab) with specificity for CD3 and for the tumor antigen CA72-4 (TAG72) on various gastrointestinal tumors. We established a hybrid/hybridoma by somatic fusion of two hybridoma lines secreting antibodies against CA72-4 and CD3 respectively and characterized its bimab OKT3/B72.3. In combination with costimulatory anti-CD28 antibodies resting peripheral lymphocytes could be activated specifically by bi-mab OKT3/B72.3 with T cell proliferation and IL-2 secretion. The bi-mab OKT3/B72.3 could also trigger the cytotoxicity of these T cells toward, CA72-4+ cells in vitro. Our results indicate, that bi-mab OKT3/B72.3 in combination with an anti-CD28 mab can redirect T cell cytotoxicity specifically against CA72-4+ tumor cells implicating a novel strategy for the specific immunotherapy of CA72-4+ tumors.

Animals↗