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Biomedical subjects

W Ruehl

Publications and source records attributed to W Ruehl.

6 recordsLinked to original sources
PubMed1997

Geriatric behavioral problems.

Behavior problems in older pets may be due to many of the same causes as in younger pets. However, the effects of aging on the pet's body may cause a dramatic decline or deterioration in organ and sensory function, which may have a profound impact on the pet's behavior. A decline in cognitive function may also afflict older pets, in many instances due to the occurrence of Alzheimer's disease brain pathology, especially beta amyloid plaque formation. Correlation of geriatric behavior problems, therefore, entails first diagnosing and treating any underlying medical problems. Behavior modification techniques and drug therapy may then be required, with modifications and adjustments made to suit the specific needs of the older pet.

Aging↗
PubMed1992

The effect of unlabelled monoclonal antibody (mAb) on the biodistribution of 131I-anti-idiotype mAb in murine B cell lymphoma.

The 38C13 murine B cell lymphoma model was used to study the effect of the preinjection of unlabelled anti-idiotype monoclonal antibody (mAb) on the subsequent biodistribution of 131I-anti-idiotype mAb. Mice with established tumors received 0-500 micrograms of unlabelled anti-idiotype mAb 24 h prior to the administration of 131I-anti-idiotype (specific), or both 125I-anti-idiotype and 131I-isotype-matched irrelevant control (nonspecific) mAb. Mice were counted daily in a gamma counter and sacrificed at 2-144 h following injection. Mice were dissected and the weight and activity of the animals and organs were measured. Mice were bled periodically and circulating idiotype levels were measured using an ELISA assay. Five hundred micrograms of unlabelled anti-idiotype mAb increased the retention time of the specific but not the nonspecific mAb in all organs and tumor. Following pretreatment with unlabelled mAb, the cumulative tumor/whole body and tumor/normal organ ratios became similar to those of the nonspecific mAb, with concentration ratios (specific/nonspecific mAb) of approximately 1, which persisted until 96 h post injection when circulating idiotype reappears in antigen excess. In the absence of unlabelled mAb there was less retention in tumor and normal tissue. This is presumed to be due in part to decreased levels of circulating 131I-mAb secondary to rapid plasma clearance of antigen-antibody complexes and tumor cell mediated dehalogenation, which results when the specific mAb specifically binds the targeted antigen. Thus, the addition of unlabelled mAb increased the retention by decreasing the specific behavior of the anti-idiotypic antibody.

Animals↗
PubMed1990

Determinants of the antitumor effect of radiolabeled monoclonal antibodies.

The murine B-cell lymphoma 38C13 model was used to study the radiobiological effect of 131I-monoclonal antibody (MAB) therapy compared with dose equivalent external beam irradiation. Continuous exponentially decreasing low dose rate (LDR) gamma-irradiation, and multiply fractionated (MF) X-irradiation were compared with dose equivalent 131I-MAB. The relative therapeutic efficacy of radioimmunotherapy, and the relative contribution of (a) low dose rate; (b) whole body irradiation; and (c) microdosimetry to the overall effect were determined. Groups of mice with or without B-cell lymphoma were treated with either (a) 131I-anti-idiotype MAB; (b) 131I-isotype-matched irrelevant control MAB; (c) 5-15 Gy 250 kV X-irradiation given as a single fraction; (d) 2.5-30 Gy 250 kV X-irradiation given in 10 fractions/2 weeks; or by (e) continuous exponentially decreasing gamma-irradiation via a 137Cs source, which simulated the effective t1/2 of the 131I-MAB. In tumor-free mice the LD50/30 was approximately 10 Gy for MF and LDR external irradiation, and 11-12 Gy for 131I-MAB. However, the effect of these modes of irradiation on tumor size differed significantly. The cumulative percentage of tumor reduction averaged over 12 days was 0.635 +/- 0.055%/Gy for MF, and 1.36 +/- 0.061%/Gy for LDR external irradiation (a relative efficacy factor of 1.63 for LDR irradiation; P = 0.01). Assuming homogeneous body distribution, the tumor reduction effect over 12 days for 131I-MAB was 2.064 +/- 0.133%/Gy for specific, and 1.742 +/- 0.1%/Gy for nonspecific isotype-matched irrelevant 131I-MAB (P = 0.02). When 131I-MAB was compared to LDR external irradiation, the relative efficacy factor was 1.99 (P less than 0.001). In summary, there was a dose rate effect on tumor response, which may in part explain the efficacy of radioimmunotherapy. The additional effect of 131I-MAB on tumor response was only partially explained by the cumulative concentration ratio of 131I-MAB tumor/131I-MAB whole body, which was on average 1.7. This relatively low concentration ratio was partly due to tumor-mediated dehalogenation. Thus, the overall tumor response was a function of the total dose, dose rate, and both the specific and nonspecific distribution of 131I-MAB.

Animals↗
PubMedDate not supplied

The canine as an animal model of human aging and dementia.

The aged canine displays many features that make it an excellent model for studying the progression of pathology in brain aging and linking these findings to learning, memory and other cognitive functions. Canines develop extensive beta-amyloid deposition within neurons and their synaptic fields, which appears to give rise to senile plaques. These plaques are primarily of the early diffuse subtype. Aged canines also exhibit accumulations of lipofuscin, cerebral vascular changes, dilation of the ventricles, and cytoskeletal changes. Neurofibrillary tangles (NFTs) are not present in the aged canine. Thus, the aged canine brain provides a suitable model for studying early degeneration normally considered to be pre-Alzheimer's. This supposition is also supported by behavioral data. We have found that the extent of beta-amyloid deposition correlates with a decline in select measures of cognitive function. These data provide the first evidence of a correlation between beta-amyloid accumulation and cognitive decline in the absence of NFTs. We summarize four lines of evidence that support using the aged canine as a model of human aging: (a) Aged canines develop aspects of neuropathology similar to that observed in aged humans; (b) Veterinarians have observed that many canines exhibit a clinical syndrome of age-related cognitive dysfunction; (c) Aged canines are deficient on a variety of neuropsychological tests of cognitive function; (d) The level of beta-amyloid accumulation correlates with cognitive dysfunction in the canine. These data indicate that the aged canine is a particularly useful model for studying age-related cognitive dysfunction (ARCD), early neuronal changes associated with aging, and the initial stages of senile plaque formation.

Aging↗