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Biomedical subjects

J S Schumacher

Publications and source records attributed to J S Schumacher.

4 recordsLinked to original sources
PubMed1998

The neurotoxicity of amyloid beta protein in aged primates.

Amyloid beta protein deposition is a universal feature of Alzheimer's disease brain. To investigate the effects of amyloid beta protein in aged primates, intracerebral microinjections of solubilized amyloid beta (A beta (1-40)) and control peptides were made into the frontal cortex of 7 primates under stereotactic guidance. Control injections consisted of vehicle alone, a 37 amino acid non toxic peptide (A37), scrambled peptide (CA4), and reverse peptide (A beta (40-1)). Amyloid beta peptide produced dose-dependent cortical lesions that were significantly larger than those produced by vehicle or by isomolar control peptides (3.28 and 2.20 fold larger respectively) (p = < 0.005). In 5 aged primates, the cortex surrounding the amyloid beta lesions contained argyrophilic, thioflavine S fluorescent, Alz 50 and ubiquitin immunoreactive neurons and perikarya. The number of Alz 50 immunoreactive neurons surrounding the amyloid beta injections was significantly greater (mean 127 +/- 39) than the number found surrounding reverse peptide injections (mean 20 +/- 13) and other control peptides (mean 0.8 +/- 0.3) (p < 0.05). Neuronal and neuritic alterations were not found adjacent to the amyloid beta peptide lesions in young monkeys and control injections produced insignificant Alz 50 neuronal positivity. These findings suggest that amyloid beta peptide is neurotoxic in primate brain and that the cytoskeletal response to amyloid beta protein is specific and age-related.

Age Factors↗
PubMed1993

Small intestinal incarceration through the lateral ligament of the urinary bladder in a horse.

Small intestinal incarceration through the lateral ligament of the urinary bladder was diagnosed in a 14-year-old, 569-kg, castrated Quarter Horse. The incarceration was corrected by ventral midline celiotomy. Approximately 70 cm of the middle portion of the jejunum was resected and end-to-end, single-layer anastomosis was performed. After surgery, the horse developed signs of adynamic ileus and lameness in the right forelimb. The horse developed laminitis in all 4 feet within 24 hours of surgery. The horse was euthanatized because of poor prognosis for survival. At necropsy, a 4.5-cm rent was found in the left lateral ligament of the urinary bladder. The cause of the rent in the ligament of this horse was not determined.

Animals↗
PubMed1993

Constraining effects of examples in a creative generation task.

In three experiments we tested the conformity hypothesis--that subjects' ideas would conform to examples they had been shown--by using a creative generation paradigm in which subjects imagined and sketched new exemplars of experimenter-defined categories. Designs made by subjects who had first seen three examples of ideas were compared with those of control subjects, who received no examples. In all three experiments, the designs of subjects who had seen the examples were more likely to contain features of the examples. This conformity effect did not significantly decrease in Experiment 2, when a 23-min task was interpolated between viewing the examples and generating related ideas. The hypothesis that the observed conformity effects may have been caused by subjects' assumptions that they should try to generate ideas similar to the examples was refuted in Experiment 3; explicitly instructing subjects to create ideas that were very different from the examples did not decrease conformity to the examples, and instructing them to conform to the examples significantly increased conformity. The results show that recent experience can lead to unintentional conformity, constraining the generation of creative ideas.

Adolescent↗