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Biomedical subjects

T Ryken

Publications and source records attributed to T Ryken.

7 recordsLinked to original sources
PubMed2000

Antisense-mediated inhibition of the bcl-2 gene induces apoptosis in human malignant glioma.

BACKGROUND: The bcl-2 protooncogene represses a number of cellular apoptotic pathways and is known to be expressed in increasing amounts in glial tumors of higher malignancy. We tested whether antisense oligonucleotides to the bcl-2 gene would affect glioma cell viability. METHODS: Antisense oligonucleotides directed to the first six codons of the human bcl-2 gene, and nonsense oligonucleotides as a control, were transfected into malignant glioma cells. Two human Bcl-2 positive glioblastoma cell lines from our tumor bank (Jon52 and Roc) were both transfected in vitro with bcl-2 antisense (AS) and nonsense (NS) oligonucleotides at 1 microm and 5 microm concentrations for 5 and 24 hr. Cell viability was assessed at 2, 4, 5, and 7 days by using an MTT mitogenic assay and by cell counting via direct visualization using a hemocytometer. RESULTS: There was up to a log-fold decrease in cell growth of the bcl-2 AS treated cells compared to the NS transfected cells for both Roc (p = 0.007 and p = 0.004) and Jon52 (p = 0.02 and p = 0.004) at 5 and 24 hr of transfection. There was as much as 50% cytotoxicity in both glioblastoma cell lines at 1 microm and 5 microm concentrations after 24 hr transfection with AS bcl-2 oligonucleotides (all p < 0.01). Western blot analysis demonstrated a decrease in the expression of the Bcl-2 protein in one cell line, whereas there was a statistically significant increase in the apoptotic index of both cell lines (p < 0.05 by chi square analysis). CONCLUSIONS: Our results suggest that transfection of human glioma cells with antisense bcl-2 results in an increase in apoptotic death. This provides evidence that Bcl-2 plays a role in tumor progression of glioma by acting as an oncogene, and suggests that inhibition of the bcl-2 gene could have a therapeutic effect.

Aged↗
PubMed1999

Virtual endoscopic environments in modern neurosurgical practice.

Modern radiographic techniques have allowed the creation of high-definition planar images that can provide important anatomical as well as physiological data. Planar imaging sets can be reformatted into three-dimensional (3-D) data sets that can then be manipulated to demonstrate important anatomical or gross pathological features. Three-dimensional data sets have been used with success in modern image-guided or frameless stereotactic surgery. Another potential application is so-called "virtual endoscopy" or "scopeless endoscopy," in which a 3-D anatomical data set is reformatted into a volume-rendered image that can then be viewed. By reformatting images in this way, a "surgeon's-eye" view can be obtained, which can aid in presurgical planning and diagnosis. The use of virtual endoscopy has the potential to increase our understanding of the appropriate anatomy and the anatomical relationships most apparent during neurosurgical approaches. In so doing, virtual endoscopy may serve as an important means of planning for therapeutic interventions. On the other hand, one must always be cognizant of the technical limitations of these studies regardless of the quality of the reconstructed images. Prospective, correlative, clinical studies in which the anatomical advantages of virtual-based endoscopy are evaluated in large cadaver or patient series must be performed. Until then, the only potential ways to compensate for errors that exist in the algorithms and reconstructions of 3-D endoscopic images are based on the surgeon's understanding of the clinical state of the patient and prior experience with the anatomy in the region of question.

Journal Article↗
PubMed1997

Restricted growth potential of rat neural precursors as compared to mouse.

Epidermal growth factor (EGF) responsive precursors isolated from the developing mouse striatum could be continually expanded in culture as free-floating spheres of cells for over 50 days. Under identical conditions, EGF-responsive precursors from the developing rat striatum could only be expanded for between 21 and 28 days, after which crisis ensued and there was a reduction in cell number at each passage. The outer regions of 28-day-old rat spheres contained a heterogeneous population of both dividing and dying cells while the cores were full of dying cells, many of which showed features consistent with apoptosis. Fibroblast growth factor-2 (FGF-2) alone did not lead to an expansion in rat striatal precursor cell number under the conditions used here. EGF combined with FGF-2 acted synergistically on cell growth, but did not prevent the final senescence and death of the rat precursors.

Animals↗
PubMed1993

Nonrheumatoid cranial settling.

Cranial settling is a condition in which erosive changes of the atlantal lateral masses result in downward telescoping of the atlas onto the axis body, anterior displacement of the atlantal posterior arch, and subsequent ventral and dorsal cervicomedullary compression. Cranial settling is described in conjunction with rheumatoid basilar invagination and atlanto-axial instability, possibly representing the most life-threatening abnormality associated with rheumatoid arthritis. The authors describe a case of symptomatic cranial settling in a nonrheumatoid patient with chronic, severe, spasmodic torticollis resulting in erosive changes in the occipito-atlanto-axial complex.

Atlanto-Axial Joint↗
PubMed1992

Botulinum toxin enhancement of postoperative immobilization in patients with cervical dystonia. Technical note.

Postoperative immobilization in patients with cervical dystonia requiring fusion presents a unique management problem. Two patients with severe degenerative cervical spine disease secondary to chronic repetitive motion are reported. Both required a surgical fusion and postoperative immobilization. Botulinum toxin was injected intramuscularly to assist in immobilization. The technique used is described.

Adult↗