Biomedical subjects

W Griffitt

Publications and source records attributed to W Griffitt.

11 recordsLinked to original sources

PubMed1999

Development of a new mouse brain tumor model using implantable micro-cannulas.

The objective of this study was to develop a brain tumor model in a mouse where gene therapy could be delivered either directly into a pre-established tumor bed or prophylacticly prior to tumor delivery (protective treatment). Micro-cannulas were constructed from metal tubing, implanted into the right frontal lobe of mice, and then secured in place in the skull with cement. Experiments evaluating the usefulness, reproducibility and morbidity of the system were performed. It was found that tumor cells could reproducibly be delivered into the right frontal lobe of the mice. Two tumors could be precisely delivered into the same area following injections at different times. Repeat injections were performed without a stereotaxic frame and without the need for repeat intracerebral needle tracts. There were no noticeable side effects of maintaining the cannulas in place for long periods of time. In summary, this system is useful for studying the effects of various treatment strategies on established brain tumors in a mouse model which more closely simulates the clinical situation. It obviates the need for time consuming stereotaxic procedures or repeat invasive intracerebral injections.

Animals↗

PubMed1998

Survival and toxicity of an allogeneic cytokine-secreting fibroblast vaccine in the central nervous system.

OBJECTIVE: In previous studies, we determined that C57BL/6 mice (H-2b) with intracerebral (i.c.) malignant glioma or melanoma treated with allogeneic fibroblasts genetically engineered to secrete interleukin (IL)-2 results in prolonged survival and a cellular antitumor response when the treatment is administered intratumorally (via i.c. injection). For this study, we evaluated the survival and toxicity of the cytokine-secreting cellular vaccine administered directly into the central nervous system in both syngeneic (C3H H-2k) and allogeneic (C57BL/6 H-2b) mice using bioassay and polymerase chain reaction techniques. METHODS: First, brain sections were prepared at varying time intervals (2-60 d) after i.c. injection of the IL-2-secreting fibroblasts (H-2k) into allogeneic and syngeneic mice, and the presence of the cells was detected by polymerase chain reaction for the neomycin gene, which was used as a selection marker for the gene transfer. As a second means of assessing survival of the IL-2-secreting cells, an in vitro bioassay technique was used. Brain sections were prepared at varying time intervals (2-60 d) after i.c. injection of the IL-2-secreting cells into allogeneic and syngeneic mice. Cells were disassociated and grown in media containing neomycin. RESULTS: A positive signal by polymerase chain reaction was no longer detectable 14 days after injection into allogeneic C57BL/6 (H-2b) mice. In contrast, under similar circumstances, the IL-2-secreting cellular vaccine could be detected for more than 55 days in histocompatible (C3H) syngeneic mice (H-2k). Allogeneic cells could be recovered from tissue culture for only 2 to 5 days after i.c. injection of the modified cells. In contrast, syngeneic cells were recovered for up to 28 days after i.c. injection. At no time did the mice exhibit signs of neurological deficit or adverse affects on their survival (>60 d). CONCLUSION: An allogeneic cytokine-secreting cellular vaccine has a limited lifespan in the central nervous system, surviving only 14 days or less, and has no apparent adverse effects. These results indicate the advantage of using a modified allogeneic cell line as the delivery vehicle for gene therapy in the treatment of an i.c. neoplasm.

Animals↗

PubMed1998

Spontaneous thoracic spinal cord herniation through an anterior dural defect.

A 44-year-old woman was examined for progressive left lower extremity weakness and spasticity. Thoracic spine MR imaging and CT myelography showed a ventral dural defect at T7-T8 with an extradural subarachnoid fluid collection and extradural herniation of the spinal cord. Intraoperative sonography confirmed the appropriate level for dural entry and the finding of spinal cord herniation. After reduction of the herniated spinal cord, the patient experienced gradual improvement in neurologic function.

Adult↗

PubMed1996

TLD array for precise dose measurements in stereotactic radiation techniques.

We developed a new TLD array for precise dose measurement and verification of the spatial dose distribution in small radiation targets. It consists of a hemicylindrical, tissue-equivalent rod made of polystyrene with 17 parallel moulds for an exact positioning of each TLD. The spatial resolution of the TLD array was evaluated using the Leskell spherical phantom. Dose planning was performed with KULA 4.4 under stereotactic conditions on axial CT images. In the Leksell gamma unit the TLD array was irradiated with a maximal dose of 10 Gy with an unplugged 14 mm collimator. The doses delivered to the TLDs were rechecked by diode detector and film dosimetry and compared to the computer-generated dose profile. We found excellent agreement of our measured values, even at the critical penumbra decline. For the 14 mm and 18 mm collimator and for the 11 mm collimator combination we compared the measured and calculated data at full width at half maximum. This TLD array may be useful for phantom or tissue model studies on the spatial dose distribution in confined radiation targets as used in stereotactic radiotherapy.

Humans↗

PubMed1975

Sexual experience and sexual responsiveness: sex differences.

Male (30) and female (30) college undergraduate subjects were shown five photographic slides depicting different heterosexual behaviors and one slide depicting solitary masturbation by a person of the same sex as the subject. Subjects rated the extent to which they found each of the slides sexually arousing and pleasant or unpleasant and indicated how many times they had personally engaged in each of the depicted activities. Following exposure to the slides, sexual arousal and emotional reactions were assessed. Contrary to the propositions of Kinsey et al. (1953), female heterosexual experience was equal to or superior to masturbation experience as an indicant of female sexual reactivity to the erotic materials. Among males, masturbation experience was superior to heterosexual experience as an indicant of sexual reactivity. The role of affective reactions to sexual experiences as determinants of sexual responsiveness is discussed.

Adolescent↗

PubMed1974