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Biomedical subjects

G Jager

Publications and source records attributed to G Jager.

9 recordsLinked to original sources
PubMed2005

Cryosurgery and radiofrequency ablation for unresectable colorectal liver metastases.

AIMS: To report immediate local treatment efficacy and long-term results of cryosurgical ablation (CSA) and radiofrequency ablation (RFA) in patients with colorectal liver metastases not eligible for resection. METHODS: Fifty-eight patients with unresectable colorectal liver metastases were included. Under ultrasound guidance, CSA or RFA were performed with or without concomitant resection. CT scanning and FDG-PET were used to determine local efficacy of the ablative procedure. RESULTS: Median follow-up was 26 and 25 months for CSA and RFA, respectively. One and 2-year survival rates were 76 and 61% for CSA and 93 and 75% for RFA, respectively. In a lesion based analysis, the local recurrence rate was 9% after CSA and 6% after RFA. Complication rates were 30 and 11% after CSA and RFA, respectively, (p=0.052). In a subgroup analysis on 43 patients with 104 ablated lesions, CT scan immediate after treatment was not able to predict local treatment failure, whereas FDG-PET scan within 3 weeks after local ablative treatment predicted six of the seven local recurrences. CONCLUSIONS: In patients with unresectable colorectal liver metastases, CSA and RFA can be used either alone or as an effective adjunct to resection in achieving complete tumour clearance of the liver. More widespread use of these techniques seems promising but requires further investigation in randomized trials comparing local ablative treatment with chemotherapy.

Aged↗
PubMed2004

F-18-fluorodeoxyglucose positron emission tomography leading to a diagnosis of septic thrombophlebitis of the portal vein: description of a case history and review of the literature.

Pylephlebitis or septic thrombophlebitis of the portal vein is a serious infectious disorder. Early diagnosis is difficult, due to nonspecific symptoms and signs, limitations of diagnostic modalities and the lack of familiarity of physicians with this entity. We report the history of a 73-year-old man with fever of unknown origin (FUO) in whom laboratory tests, blood and urine cultures, chest X-ray, abdominal ultrasound, and Indium-111-leucocyte scintigraphy did not reveal the cause of the fever. F-18-fluorodeoxyglucose (FDG) positron emission tomography (PET) subsequently pointed to the diagnosis of pylephlebitis, which was confirmed by computed tomography (CT) and percutaneous puncture. We conclude that FDG PET allows detecting inflammatory foci in patients with FUO and offers to make the diagnosis of pylephlebitis at an early stage.

Aged↗
PubMed2003

Neurophysiological factors in human information processing capacity.

What determines how well an individual can manage the complexity of information processing demands when several tasks have to be executed simultaneously? Various theoretical frameworks address the mechanisms of information processing and the changes that take place when processes become automated, and brain regions involved in various types of information processing have been identified, as well as sequences of events in the brain. The neurophysiological substrate of human information processing capacity, i.e. the amount that can be processed simultaneously, is, however, unresolved, as is the basis of inter-individual variability in capacity. Automatization of cognitive functions is known to increase capacity to process additional tasks, but behavioural indices of automatization are poor predictors of processing capacity in individuals. Automatization also leads to a decline of brain activity in the working memory system. In this study, we test the hypothesis that processing capacity is closely related to the way that the brain adjusts to practice of a single cognitive task, i.e. to the changes in neuronal activity that accompany automatization as measured with functional MRI (fMRI). Using a task that taxes the working memory system, and is sensitive to automatization, performance improved while activity in the network declined, as expected. The key finding is that the magnitude of automatization-induced reduction of activity in this system was a strong predictor for the ability to perform two different working memory tasks simultaneously (after scanning). It explained 60% of the variation in information processing capacity across individuals. In contrast, the behavioural measures of automatization did not predict this. We postulate that automatization involves at least two partially independent neurophysiological mechanisms, i.e. (i) streamlining of neuronal communication which improves performance on a single task; and (ii) functional trimming of neuronal ensembles which enhances the capacity to accommodate processing of additional tasks, potentially by facilitating rapid switching of instruction sets or contexts. Finally, this study shows that fMRI can provide information that predicts behavioural output, which is not provided by overt behavioural measures.

Adult↗
PubMed2003

Attentionally modulated effects of cortisol and mood on memory for emotional faces in healthy young males.

Heightened cortisol levels due to stress or acute administration seem to enhance memory for emotional material, independently of emotional valence. An arousal-driven neurobiological mechanism involving the amygdala has been proposed. The relation between pre-task salivary measures of cortisol (by convention named 'basal levels') and emotionally modulated memory has not been investigated yet. Given the association between higher basal levels of cortisol and indices of low mood, valence-specific effects on emotionally modulated memory could be expected (e.g. mood-congruent or stimulus-specific forms of processing). This study was designed to investigate the relationship between basal levels of salivary cortisol, self-reported mood and spatial memory for neutral, happy and angry facial expressions in healthy young volunteers (N=31). Memory performance was indexed using a modified version of a computerized object-relocation task, using emotional facial expressions as stimuli. Results showed a significant relation between cortisol and depressive mood. More importantly, both the levels of cortisol and depressive mood were inversely related to the memory performance for the happy facial expressions, while a similar relationship between cortisol and memory performance on angry faces neared significance. An explanation in terms of the down-regulation of social behavior by elevated basal cortisol levels is postulated.

Adult↗
PubMed1996

Lenticular astigmatism after penetrating eye injury.

Lenticular astigmatism of 5.00 diopters developed after penetrating injury in the eye of a 16-year-old boy. Full visual acuity, refraction, and crystalline lens clarity remained stable for more than 2 years. The high astigmatism, in conjunction with a spherical cornea and posterior lens capsule striae, indicates the lenticular origin of the astigmatism.

Adolescent↗
PubMed1996

Polymerase chain reaction for diagnosis and identification of distinct variants of Crimean-Congo hemorrhagic fever virus in the United Arab Emirates.

Viral hemorrhagic fever has re-emerged in the United Arab Emirates (UAE) since November 1993. Genomic RNA of Crimean-Congo hemorrhagic virus (C-CHFV) was detected by a newly developed, nested reverse transcriptase polymerase chain reaction (RT-PCR) in the sera of four (25.0%) of 16 suspected cases of viral hemorrhagic fever. The RT-PCR was based on oligonucleotide primers deducted from the small RNA segment encoding the nucleoprotein of the virus. By comparison with a nucleotide sequence of a C-CHFV isolate from a Chinese sheep, a divergence of 10.0-11.8% was detected in the C-CHFV variants causing the UAE outbreak. In the four positive sera, three phylogenetically distinct C-CHFV variants were amplified and confirmed by direct sequencing of the PCR fragments. These C-CHFV sequences were obtained directly from sera of infected humans without prior propagation in cell culture. The RT-PCR allows rapid detection of genomic C-CHFV RNA in clinical specimens and study of the molecular epidemiology of this infection.

Amino Acid Sequence↗
PubMed1995

Staging urinary bladder cancer: value of T1-weighted three-dimensional magnetization prepared-rapid gradient-echo and two-dimensional spin-echo sequences.

OBJECTIVE: The purpose of this study was to evaluate a magnetization prepared-rapid gradient-echo (MP-RAGE) sequence as a three-dimensional T1-weighted MR imaging technique for staging urinary bladder cancer and to compare this technique with a commonly used two-dimensional T1-weighted spin-echo sequence technique. SUBJECTS AND METHODS: For 28 consecutive patients with urinary bladder cancer, MR findings and staging results were compared with histopathologic findings after surgery or autopsy. MR imaging was performed at 1.5 T with a Helmholtz double-surface coil. Conventional T1-weighted spin-echo, three-dimensional MP-RAGE, T2-weighted spin-echo or turbo-spin-echo, and dynamic T1-weighted fast gradient-echo sequences were used. Signal difference-to-noise ratios and T1 contrast were calculated by use of operator-defined regions of interest. RESULTS: The signal difference-to-noise ratios for fluid-tumor and fat-tumor were, respectively, factors of 1.6 and 2.7 better with T1-weighted spin-echo sequences. T1 contrast of fluid-tumor was a factor of 2.6 better with three-dimensional MP-RAGE sequences, resulting in better recognition of small tumors, ascites, and dilated ureters. T1 contrast for fat-tumor was a factor of 2.0 better with T1-weighted spin-echo sequences. With the MP-RAGE sequence, motion artifacts were fewer in number than those noted with the T1-weighted spin-echo sequence, and susceptibility artifacts were equal in number to those noted with the T1-weighted spin-echo sequence. Using the three-dimensional technique, we performed off-line reconstruction of 1- to 2-mm high-resolution images in every desired plane. Because of higher spatial resolution, the availability of multiplanar reconstructions, and better fluid-tumor contrast and despite lower signal difference-to-noise ratios, three-dimensional MP-RAGE images resulted in better recognition of local tumor extension (n = 11), adhesions and bowel wall invasion (n = 5), lymph node metastases (n = 2), and bone marrow metastases (n = 2). The staging accuracy for the combination of three-dimensional MP-RAGE, T2-weighted, and dynamic sequences was 93%; that for the combination of two-dimensional T1-weighted spin-echo, T2-weighted, and dynamic sequences was 78%. Nodal staging was also more accurate with MP-RAGE sequences (accuracy of 93% vs 86% for T1-weighted spin-echo sequences). CONCLUSION: Compared with two-dimensional T1-weighted spin-echo imaging, three-dimensional MP-RAGE imaging resulted in a 15% improvement in staging. Our findings suggest that optimal staging of urinary bladder carcinoma requires three-dimensional imaging techniques.

Adult↗
PubMed1986

Frequent lambda light chain gene rearrangement and expression in a Ly-1 B lymphoma with a productive kappa chain allele.

We describe here a murine Ly-1-bearing pre-B-cell tumor that, when induced for kappa light chain expression with bacterial lipopolysaccharide, also gives rise spontaneously to a few percent of cells expressing surface lambda light chains. These lambda-positive cells have undergone DNA rearrangements involving either V lambda 1 or V lambda 2 genes. Nearly all clones of lambda-bearing cells express mu and lambda on their surface (but not kappa). However, all these lambda-positive clones continue to transcribe kappa mRNA and synthesize internal kappa chains. Further, surface lambda-positive clones show JH rearrangements on one or both heavy chain chromosomes.

Animals↗